JP6255671B2 - Inverter - Google Patents

Description

  The present invention relates to a power conditioner used for a photovoltaic power generation system or the like.

  This type of conventional power conditioner is also referred to as a grid-connected inverter, and is disclosed, for example, in Patent Document 1 below. This conventional power conditioner includes a non-insulated DC / DC converter (boost circuit 4) for boosting and stabilizing DC generated power supplied from a photovoltaic power generation panel, and DC power output from the converter. A DC / AC inverter (sine wave generation circuit 5) that converts the AC power into the AC power and outputs the AC power. The converter and the inverter are normally connected via a DC link capacitor (DC link unit) as disclosed in Patent Document 2 and the like. This DC link capacitor stabilizes the output waveform by providing a ripple filter function and stabilizing the input voltage of the inverter, and is controlled by the control unit so that the voltage across the DC link capacitor becomes the target voltage. The operation of the converter is controlled.

  While photovoltaic power generation is allowed to be sold due to the reverse power flow to the commercial power system, the output of the inverter is taken into consideration for the adverse effects on other customers and the obstacles to the maintenance of facilities of electric utilities and other customers. It is obliged to provide a disconnection protection relay (disconnection switch) on the side, and further, it is required to ensure the normal operation of the protection relay.

  In the technique described in Patent Document 1, a voltage detector 9 for confirming the disconnection operation is added between the inverter and the protection relay, the voltage detector 9 in a state where the inverter circuit unit is stopped and the protection relay is turned off. It is configured to determine whether or not the protection relay is normal based on the detected value.

  Further, in the technique described in Patent Document 2, when the inverter circuit is controlled to be stopped and the grid connection relay is controlled to be in the open state, the first contact portion and the second that constitute the grid connection relay For the contact portion, the potential difference between the X side of the first contact portion and the Z side of the second contact portion and the potential difference between the Y side of the first contact portion and the X side of the second contact portion are respectively determined by a photocoupler. By detecting, before connecting an inverter circuit and a commercial power system, it is comprised so that it may detect whether each contact part is welded.

Japanese Patent No. 3979278 JP 2011-135767 A

  Both of Patent Documents 1 and 2 require an unnecessary voltage detector or photocoupler during normal operation, and an increase in the number of parts causes an increase in cost and also requires maintenance management of these additional parts.

  On the other hand, a voltage source bridge inverter is generally employed as the inverter of the power conditioner, and this voltage source bridge inverter is mainly composed of an H bridge circuit in which four switching elements are connected in an H shape, A feedback diode is connected in parallel to the switching element, and an AC waveform linked to the system power is output by controlling the voltage source bridge inverter in a current mode. Further, a boost chopper circuit is generally employed as the converter. Due to such a circuit configuration, when the disconnection protection relay is closed (parallel control) when the control of the converter and the inverter is stopped, the system power is supplied to the DC link capacitor via the feedback diode. The voltage at both ends rises to near the maximum value of the AC system voltage. On the other hand, when the disconnection protection relay is controlled to open (disconnection control), the voltage on the input side of the converter passes through the step-up chopper circuit and is applied to the DC link capacitor as it is. If it is lowered, the voltage across the DC link capacitor is also lowered.

  The present invention has been made by applying the above knowledge, and by enabling failure determination of the disconnection protection relay using the circuit configuration used during normal operation, the number of parts can be reduced, The purpose is to simplify the circuit configuration and to reduce the cost.

  In order to achieve the above object, the present invention takes the following technical means.

That is, the power conditioner of the present invention connects the DC link unit, the converter that boosts the power supplied from the power generation unit and outputs the boosted power to the DC link unit, and the power supplied from the DC link unit to the system power. An inverter that converts and outputs AC power to the system, DC link voltage detection means that detects the voltage of the DC link unit, a first disconnection protection relay provided on the output side of the inverter, and the converter A control unit for controlling the inverter and the protection relay, and the inverter has a circuit configuration capable of supplying system power to the DC link unit when a contact of the protection relay is closed. The disconnection operation abnormality is determined based on the relationship between the control command content to the protection relay when the predetermined condition is satisfied and the detected value of the DC link voltage detecting means. It is characterized in that it has a function (claim 1).

  According to the power conditioner of the present invention, if the protection relay is normal, when the protection relay is controlled to open, the DC link unit is electrically disconnected from the system, and the DC link voltage is generated by the power generation unit and the converter operation. While the voltage depends on the state, when the protection relay is closed, the DC link unit is electrically connected to the system, and the DC link voltage is affected by the system power. On the other hand, when the protective relay is fixed with the contact closed by, for example, welding, the DC link portion is not electrically disconnected from the system even if the protective relay is controlled to open, and the DC link voltage is to be influenced. Therefore, by properly setting the predetermined condition, it is possible to determine the disconnection operation abnormality based on the relationship between the content of the control command to the protection relay and the detected value of the DC link voltage detecting means. Since it is possible to determine the abnormality of the protection relay using the DC link voltage detection means for detecting the DC link voltage that becomes the control parameter of the converter during system operation, the number of parts can be reduced and the circuit configuration can be simplified. Can do.

  The disconnection operation abnormality determination function can be realized by executing a predetermined control flow, and can be configured to determine the predetermined condition at the beginning of the control flow. The predetermined condition includes one or more of various conditions for directly or indirectly determining a state where the power generation output of the power generation unit is insufficient and the DC link voltage cannot be maintained at the target voltage during normal interconnection operation. be able to. For example, it can be included as a predetermined condition that it is a night time zone in which the amount of sunshine is insufficient, and the night time zone is based on current time data indicated by a built-in clock of the control unit or current time data input from the outside Can be determined. Moreover, it can include as a predetermined condition that the input voltage from the power generation unit to the converter is less than a predetermined voltage, and the input voltage may be measured by a voltage sensor provided between the power generation unit and the converter. In addition, if the converter has a circuit configuration in which the input voltage is directly applied to the output side when the control is stopped, such as a boost chopper circuit, the disconnection protection relay is opened and the converter is stopped. It is also possible to use the detection value of the DC link voltage detection means by regarding it as the input voltage to the converter. In addition, the number of executions of the predetermined control flow can be limited, for example, once a day.

  Preferably, the control unit can be provided with an informing means for informing an abnormality when it is determined that the disconnection operation is abnormal. According to this, it is possible to promptly notify the user or the like that an abnormality has occurred and to prompt repair. Further, it is preferable that the control unit is configured to prohibit the control of the converter and the inverter when it is determined that the disconnection operation is abnormal.

Further, as the predetermined condition, the control of the converter may include stopped (claim 1). Furthermore, it can also be included as a predetermined condition that the control of the inverter is also stopped. According to this, it is possible to avoid disconnection operation abnormality determination by avoiding that the DC link unit is boosted to a predetermined voltage or more by the operation of the converter or the voltage of the DC link unit becomes unstable by the operation of the inverter. It can be done reliably. Even if the converter is operating in the disconnected state, it is not always necessary to stop the converter if the DC link voltage is less than the predetermined voltage, and the inverter operates in the parallel state. However, if the voltage of the DC link portion becomes higher than the predetermined voltage, it is not always necessary to stop the inverter.

Incidentally, the control section, if the detected value of the DC link voltage detection means the protective relay in the open control state is intended to determine that there is an abnormality in the disconnection operation and higher than the predetermined voltage, the contact of the protection relay Even though the control unit controls the protection relay so as to open the power, the contact of the protection relay remains closed, so that the system power is supplied to the DC link unit and the DC link voltage becomes higher than the predetermined voltage. An abnormality determination based on being present can be performed. The state in which the protection relay is controlled to open includes a state in which a command signal is not sent from the control unit to the protection relay, and the protection relay may be configured to open the contact autonomously when there is no control command. it can.

The control circuit further includes a second disconnection protection relay connected in series to the first disconnection protection relay, wherein the first and second protection relays can be controlled to open and close independently. When the detection value of the DC link voltage detecting means is higher than a predetermined voltage in a state where the first protection relay is opened and the second protection relay is closed, and / or the second protection relay is opened. when the detected value of the DC link voltage detecting means controlling and the first protective relay while closing control is higher than a predetermined voltage, has good been made to determine that there is an abnormality in the disconnection operation. According to this, in the case where the reliability of the disconnection operation is further secured by the two-stage protection relay, one of the protection relays is closed by controlling the opening of one of the protection relays and closing the other protection relay. It is possible to determine an abnormality in the disengagement operation due to the sticking. Note that if an abnormality occurs in only one of the first and second protection relays, it may be determined that the disconnection operation is abnormal, and even if any one of the protection relays is abnormal, the disconnection operation is performed. It may be determined that there is an abnormality in the disconnection operation when an abnormality occurs in both of the protective relays without determining that there is an abnormality.

The control circuit further includes a second disconnection protection relay connected in series to the first disconnection protection relay, wherein the first and second protection relays can be controlled to open and close independently. Is configured to stop the control of the converter before opening the first and second protection relays when disconnecting from a state parallel to the system, and the control unit is disconnected from the system. In order to achieve this, one of the first and second protection relays is opened first and then the other is opened with a time difference. The one protection relay is opened and then the other protection relay is opened. If the detected value of the DC link voltage detecting means does not become lower than a predetermined voltage before the control, it may be determined that there is an abnormality in the disconnection operation (claim 1 ). According to this, when the power generation amount falls in the evening or when the power is disconnected from the system due to various other factors, the first and second protection relays are sequentially opened with a time difference to perform the opening control first. It is possible to determine the abnormality of the performed protection relay. When the protective relay is opened and closed, a relatively loud sound is heard, and if the protective relay is opened or closed at a time when the disconnection operation is not performed (such as at night), the user may feel uneasy. However, according to the present invention, it is possible to determine the abnormality of one of the protection relays at the timing of the original disconnection operation without causing anxiety to the user.

Further, the control unit is preferably configured to change the order of the opening control of the first and second protective relay for each paralleled operation (claim 2). According to this, one of the first and second protection relays can be sequentially inspected for each disconnection operation.

The inverter is a voltage-type bridge inverter, and is configured such that when the contact of the protection relay is closed, system power is supplied to the DC link unit via a feedback diode that constitutes the voltage-type bridge inverter. (Claim 3 ). According to this, by closing the contact of the protective relay, the DC link unit is boosted to the vicinity of the maximum value of the AC system voltage, and the disconnection operation abnormality determination is performed with the value in the vicinity of the maximum value of the system voltage as the predetermined voltage. It can be carried out.

As described above, according to the power conditioner according to claim 1 of the present application, if the normal protective relay, DC link portion when opening control protection relay is electrically disconnected from the grid, DC link voltage The voltage depends on the power generation amount of the power generation unit and the operation state of the converter, and when the protection relay is closed, the DC link unit is electrically connected to the system, and the DC link voltage is affected by the system power. On the other hand, when the protective relay is fixed with the contact closed, for example, by welding, the DC link portion is not electrically disconnected from the system even if the protective relay is controlled to open, and the DC link voltage is affected by the system power. Receive. Therefore, by properly setting the predetermined condition, it is possible to determine the disconnection operation abnormality based on the relationship between the content of the control command to the protection relay and the detected value of the DC link voltage detecting means. Since it is possible to determine the abnormality of the protection relay using the DC link voltage detection means for detecting the DC link voltage that becomes the control parameter of the converter during system operation, the number of parts can be reduced and the circuit configuration can be simplified. Can do.

Further, according to the power conditioner according to claim 1 of the present application, when the power generation amount decreases in the evening or when the power is disconnected from the system due to various other factors, the first and second protection relays are provided with a time difference. By performing sequential opening control, it is possible to determine the abnormality of the protection relay that was previously controlled to open, and to determine the abnormality of one of the protection relays at the timing of the original disconnection operation without causing anxiety to the user be able to.

It is a schematic block block diagram of a solar power generation system provided with the power conditioner which concerns on the 1st Embodiment of this invention. It is a control flowchart of the disconnection operation abnormality determination function of the same inverter. It is a schematic block block diagram of a solar energy power generation system provided with the power conditioner which concerns on the 2nd Embodiment of this invention. It is a control flowchart of the disconnection operation abnormality determination function of the same inverter. It is a control flowchart of the disconnection operation abnormality determination function of the power conditioner which concerns on the 3rd Embodiment of this invention.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.

  FIG. 1 shows a solar power generation system according to a first embodiment of the present invention. The power generation system uses a solar power generation unit 1 and direct-current power supplied from the power generation unit 1 as a single-phase three-wire commercial system power. The power conditioner 2 is mainly composed of a power conditioner 2 that converts the AC power into grid power and outputs it to the commercial power system.

  The photovoltaic power generation unit 1 may have a conventionally known appropriate configuration, and generally includes a plurality of photovoltaic power generation panels installed on the roof of a building, and the power generation output of the panel is a power conditioner 2. Is output to the input side of the converter 4. In addition, as a power generation output of a photovoltaic power generation panel, it can be set as the thing of about 100-140V, for example. When the amount of power generated by the solar power generation panel is insufficient, for example, when the solar power generation panel is not irradiated with direct sunlight such as early morning, evening, or bad weather, the input voltage of the converter 4 decreases according to the amount of sunlight. Further, a voltage sensor 19 for measuring the voltage of the electric power supplied from the power generation unit 1 to the power conditioner 2 is provided between the power generation unit 1 and the power conditioner 2, and a detection value of the voltage sensor 19 will be described later. It is input to the control unit 7 and used as various control parameters.

  The power conditioner 2 has a DC link unit 3 constituted by a DC link capacitor and a DC power supplied from the power generation unit 1 corresponding to a maximum value of an AC system voltage (for example, 280 V in the case of 200V AC power). A DC / DC converter 4 composed of a boost chopper circuit that boosts the voltage to a voltage (for example, 350 V) and outputs it to the DC link unit 3, and converts DC power supplied from the DC link unit 3 into AC power linked to the system power. A voltage source bridge inverter 5 (DC / AC inverter) for output to the system side, two disconnection protection relays 6 (first and second protection relays) provided on the output side of the inverter 5, A control unit 7 for controlling the converter 4, the inverter 5 and the protection relay 6, and a DC link voltage sensor for detecting the voltage across the DC link unit 3. 8 a (DC link voltage detection means), the detected value of the voltage sensor 8 is utilized mainly as output control parameters of the converter 4 is inputted to the control unit 7. A filter circuit 9 composed of an LC low-pass filter or the like is provided on the output side of the two protection relays 6, and the output side of the filter circuit 9 is connected to a single-phase three-wire system.

  Two protection relays 6 are connected in series, and each protection relay 6 can be controlled to open and close independently by the control unit 7. That is, each protection relay 6 is configured to close its contact when a close control command is issued from the control unit 7 and to open the contact when an open control command is issued from the control unit 7. Generally, a so-called normally open type relay in which a state in which a voltage is applied to the protection relay 6 is a close control command and a state in which no voltage is applied to the protection relay 6 is an open control command is employed.

  The control unit 7 is mainly configured by a microcomputer, and each control function is implemented as a control program, but may be configured by a dedicated circuit corresponding to each control function.

  The step-up chopper circuit that constitutes the converter 4 includes a step-up reactor 41, a step-up rectifier 42 that prevents backflow of current during step-up operation to the step-up reactor 41, and an IGBT or the like that controls the stored energy of the step-up reactor 41. The cathode side of the rectifier 42 is connected to the positive side of the DC link capacitor 3. The control unit 7 is configured to perform input / output power control of the converter 4 by PWM control of the switching element 43.

  The inverter 5 is a full-bridge type voltage-type bridge inverter, and is configured by connecting four switching elements 51 such as IGBTs in an H-bridge type and connecting a feedback diode 52 to each switching element 51 in parallel. The interconnection reactor 15 is provided on the output side. The inverter 5 controls the output current by performing so-called current mode control (current control of the voltage source inverter). When power is output to the system, the DC power from the DC link unit 3 is controlled by PWM control or PAM. The AC power is converted into AC power by the control, and the AC power is converted into a complete sine wave by the filter circuit 9 and output to the system.

  Further, in the present embodiment, the power conditioner 2 is operated by the generated power during the daytime power generation, and the power conditioner 2 is operated by the system power at night when power generation is not possible. Specifically, the power conditioner 2 includes a regulator 10 that functions as a power source for the control unit 7 and a power lead-in wiring 11 for supplying DC power from the DC link unit 3 to the power input terminal of the regulator 10. The wiring 11 is provided with a backflow prevention diode 12, and the controller 7 is operated using power from the DC link unit 3 as a power source during power generation. Further, an auxiliary power circuit for rectifying the system power to DC power via a rectifying means 13 such as a diode bridge and supplying the power to the power input terminal of the regulator 10 is provided. Means 13 and a relay 14 for turning on and off the supply of system power are provided. This relay 14 is also controlled by the control unit 7. For example, when the voltage of the DC link unit 3 becomes less than the voltage necessary for the operation of the control unit 7 to be closed, the relay 14 is closed and the control unit receives the supply of system power. 7 can be continued, and when the voltage of the DC link portion 3 becomes sufficiently high, the relay 14 is controlled to be opened. The diode 12 serves to prevent the system power from being supplied to the DC link unit 3 via the lead-in wiring 11 when the system power is supplied.

  In such a circuit configuration of the power conditioner 2 of the present embodiment, when the control of the converter 4 is stopped, the input voltage of the converter 4 has a slight forward voltage drop in the step-up rectifier 42 but is almost directly applied to the DC link unit 3. Applied. Therefore, as soon as the power generation output voltage of the power generation unit 1 drops and the control of the converter 4 is stopped, the voltage of the DC link unit 3 immediately decreases to the vicinity of the input voltage of the converter 4, for example, about 100 to 140 V, and thereafter gradually descend.

  When the control of the inverter 5 is stopped and the two protection relays 6 are closed, the four feedback diodes 52 of the inverter 5 function as an AC-DC conversion diode bridge, and the AC system power is rectified to DC. Thus, the DC link unit 3 is charged to the vicinity of the maximum value of the system voltage, for example, to a level exceeding 280V when the system is 200V AC power.

  By utilizing such characteristics, the control unit 7 according to the present embodiment has a relationship between the content of the control command to each protection relay 6 and the DC link voltage value detected by the DC link voltage sensor 8 under the condition where no power is generated. Is provided with a function of determining abnormality of the disconnection operation based on the above. Such a disconnection operation abnormality determination function can be realized, for example, by a control flow executed in the control unit 7 once a day, and an example of this control flow is shown in FIG.

  In the control flow of the disconnection operation abnormality determination function shown in FIG. 2, it is first determined whether or not it is nighttime as a first condition for determining abnormality of the disconnection operation (step S1). Not to run. Whether or not it is nighttime may be determined by using current time data indicated by a clock built in the control unit 7 based on whether the current time is a predetermined time of nighttime, or the power generation unit 1 If the detected value of the voltage sensor 19 that detects the output voltage of the output voltage is less than a predetermined low voltage (for example, less than 80 V, for example), it may be determined that the night.

  Next, as a second condition for determining abnormality of the disconnection operation, whether the control of the converter 4 and the inverter 5 is stopped and the disconnection control is being performed, that is, both the two protection relays 6 are It is programmed to determine whether or not the opening control is performed (step S2), and to perform the disconnection operation abnormality determination only when such a condition is satisfied.

  In the present embodiment, when the first and second conditions are satisfied, abnormality determination is sequentially performed for three patterns of control command contents of the two protection relays 6. That is, first, it is determined whether the DC link voltage is higher than a predetermined voltage (for example, 280 V) lower than the maximum value of the system voltage even though both of the two protection relays 6 are under open control. (Step S3). At this time, if the DC link voltage is higher than the predetermined voltage, it is determined that an abnormality has occurred in the disconnection operation, and the occurrence of an abnormality in the protective relay is notified by a display device, a sound generator, or the like (step S4). Note that, at the time of abnormality determination, it is preferable to configure the control unit 7 so that control of the converter 4 and the inverter 5 is not started even if the power generation output of the power generation unit 1 increases. Further, the predetermined voltage can be set to, for example, about 250 V with a certain margin with respect to the maximum value of the system voltage. Further, the step S3 need not be provided, and in this case, it is possible to omit the determination of whether or not the disconnection control is being performed in the step S2.

  When the DC link voltage is 280 V or less in step S3, next, the first protection relay 6 is controlled to open and the second protection relay 6 is controlled to close (step S5). (Step S6). If it is higher, it is considered that the contact of the first protective relay 6 is fixed in the closed state. Migrate to At this time, it is also possible to notify the abnormality so that it can be identified which of the protective relays 6 has failed.

  When the DC link voltage is 280 V or less in step S6, next, the second protection relay 6 is controlled to open and the first protection relay 6 is controlled to close (step S7), and the DC link voltage is set to a predetermined voltage. (Step S8). If it is higher, it is considered that the contact of the second protective relay 6 is fixed in the closed state. The process proceeds to S4. At this time, it is also possible to notify the abnormality so that it can be identified which of the protective relays 6 has failed.

  If no abnormality is determined, both protection relays 6 are opened and the execution of the disconnection operation abnormality determination function is terminated. In addition, since the contact fixation of the protection relay 6 does not occur frequently, execution of this function is limited to the number of executions during a predetermined period, such as once a day.

  In step S6 and step S8 of the control flow, when an abnormality is detected in one of the protection relays 6, the process proceeds to step S4 and it is determined that an abnormality has occurred in the disconnection operation. It can also be determined that an abnormality has occurred in the disconnection operation when an abnormality is detected in both of the two protection relays 6. In this case, even if an abnormality in one of the protection relays 6 is detected, the disconnection operation is detected. Since the operation itself can be performed, it is possible to operate the power conditioner 2 without determining that an abnormality has occurred in the disconnection operation. However, it is also possible to display on the display screen or the like that any one of the protection relays has a failure.

  3 and 4 show a power conditioner 2 according to a second embodiment of the present invention. The same components as those in the first embodiment are denoted by the same reference numerals, detailed description thereof is omitted, and different configurations are illustrated. The effect will be described.

  In the present embodiment, an auxiliary power circuit for receiving power supply from the system is not provided, and the control unit 7 operates only with the generated power supplied from the DC link unit 3. Therefore, at night when power is not generated, the control unit 7 is stopped due to power interruption, the photovoltaic power generation panel starts to generate power, and when the DC link voltage reaches about 70V, the control unit 7 is activated and the DC link voltage is 100V. The controller 7 is configured to start the interconnected operation when the degree is reached.

  In the present embodiment, the disconnection operation abnormality determination of the protection relay 6 is performed at the start of this interconnection operation. That is, before starting the grid operation, the control of the converter 4 and the inverter 5 is stopped, and both protection relays 6 are opened to be disconnected, so that the DC link voltage at the start of the grid operation is As shown, it is about 100V. On the other hand, when both protection relays 6 are closed before the control of the converter 4 is started, the system power is supplied to the DC link unit 3 and the DC link voltage rises to about 280 V, but one of the protection relays 6 is controlled to open. If this is the case, the DC link voltage should not rise, and this is used to detect contact welding of the protective relay 6.

  FIG. 4 shows an example of the control flow of the disconnection operation abnormality determination function in the present embodiment. The difference from the control flow of FIG. 2 described above will be described. This is executed immediately before the start of interconnection operation. Since the power conditioner 2 of the present embodiment is not provided with an auxiliary power circuit, depending on the configuration of the control unit 7, there may be a case where the control parameters when the power is last turned off remain in the nonvolatile memory. When it is not determined in step S2 that the control of the converter 4 and the inverter 5 is stopped and the disconnection control is being performed based on the data remaining in the control unit 7, the control state of the converter 4 and the inverter 5 is determined. Is reset and stopped, and at the same time, control is performed so that both protective relays 6 are disconnected (step S11).

  In step S3, a situation in which the DC link voltage already exceeds the predetermined voltage for some reason other than the grid power being supplied to the DC link unit 3 may be considered depending on the power generation system configuration. The column operation abnormality determination is skipped and the process proceeds to step S9.

  In step S9, the two protection relays 6 are once opened to be disconnected, and then the normal interconnection operation control is started, the control of the converter 4 and the inverter 5 is sequentially started, and both the protection relays 6 are closed. By doing so, the power conditioner 2 is made parallel to the system, and the generated power is output to the system.

  According to the present embodiment, since it is possible to determine the abnormality of the protection relay 6 immediately before the start of power generation, whether or not the disconnection operation is normally performed at the start of operation even if the protection relay 6 is left unused for a long period of time. It is possible to confirm that the connected operation is not performed when an abnormality is detected.

  FIG. 5 shows a control flow of the disconnection operation abnormality determination function of the power conditioner 2 according to the third embodiment of the present invention. In this embodiment, during the disconnection operation such as when the power generation amount decreases in the evening or the like. Execute the disconnection operation abnormality judgment function.

  The control flow of the disconnection operation abnormality determination function of the present embodiment will be specifically described. When the control unit 7 detects a decrease in the amount of power generation based on the detection value of the voltage sensor 19 or the like (step S12), the control unit 7 stops the control of the converter 4 and the inverter 5 while maintaining the closed control state (parallel state) of both protection relays 6 (step S13). Then, the DC link voltage should be about 280 V, which is near the maximum value of the system voltage, but if it is not near 280 V (step S14), it means that some abnormality has occurred, so appropriate error processing is performed. Perform (step S19). In addition, as abnormality in this case, the failure of the voltage sensor 8, a disconnection, the failure of each component which comprises the inverter 5, etc. can be considered, for example. Note that it is possible to execute the disconnection operation abnormality determination function of the present embodiment not only when the power generation amount decreases but also during a disconnection operation due to other factors.

  If it is confirmed that the DC link voltage is close to 280 V, one of the first and second protection relays A is controlled to open, and the other protection relay B is closed (step S15). . Then, since the DC link unit 3 is electrically disconnected from the system, the DC link unit 3 should be a voltage in the vicinity of the input voltage of the converter 4 where the power generation amount is reduced and becomes a low voltage. If the voltage does not reach the vicinity (step S16), it is considered that the contact of one of the protection relays A is closed and fixed, so that it is determined in step S4 that an abnormality has occurred in the disconnection operation and protection is performed. Relay error notification is performed. In step S16, it is only necessary to detect that the DC link voltage has greatly decreased from the maximum value of the system voltage. As an example, the DC link voltage is compared with an input voltage that is lower than the maximum value of the system voltage. However, the DC link voltage may be compared with a predetermined voltage that is higher than the input voltage and lower than the maximum value of the system voltage.

  On the other hand, if the DC link voltage is close to the input voltage, it can be confirmed that one of the protection relays A is operating normally, and the other protection relay B is controlled to open and the disconnection operation is performed by opening the two protection relays. Complete. Further, in order to perform the determination of the other protection relay by changing the order of opening control of the two protection relays at the next disconnection operation, the correspondence between the first and second protection relays 6 and the protection relays A and B The relationship is exchanged (step S18). Such a correspondence relationship can be stored in a nonvolatile memory built in the control unit 7.

  According to the present embodiment, it is possible to determine the occurrence of an abnormality in the disconnection operation due to the closed adhering of one protection relay by providing a time difference in the open control of the two protection relays 6 during the disconnection operation. Since the protection relay 6 is not opened / closed only for determining the row operation abnormality, it is possible to avoid noise during operation of the protection relay 6 at an unexpected timing.

  The present invention is not limited to the above-described embodiments, and the design can be changed as appropriate. For example, even if the inverter is an insulation type, a configuration in which system power is supplied to the DC link unit when the protection relay is operated in parallel by an induced voltage is also conceivable. Thus, it is possible to implement the disconnection operation abnormality determination function of the present invention. One protective relay may be provided, or three or more protective relays may be provided. Further, the predetermined condition for determining the disconnection operation abnormality may include that the input voltage from the power generation unit to the converter is lower than the maximum value of the system power voltage.

DESCRIPTION OF SYMBOLS 1 Power generation part 2 Power conditioner 3 DC link part 4 Converter 5 Inverter 6 Protection relay 7 Control part 8 DC link voltage detection means

Claims (3)

A DC link unit, a converter that boosts the power supplied from the power generation unit and outputs the boosted power to the DC link unit, and converts the power supplied from the DC link unit into AC power linked to the system power for output Controls an inverter, DC link voltage detection means for detecting the voltage of the DC link unit, a first disconnection protection relay provided on the output side of the inverter, the converter, the inverter and the protection relay And the inverter has a circuit configuration capable of supplying system power to the DC link unit when a contact of the protection relay is closed, and the control unit is configured to satisfy a predetermined condition. In a power conditioner having a function of performing abnormality determination of a disconnection operation based on the relationship between the content of the control command to the DC link and the detection value of the DC link voltage detection means ,
The predetermined condition includes stopping the control of the converter,
A second disconnection protection relay connected in series to the first disconnection protection relay; the first and second protection relays can be independently controlled for opening and closing; Is configured to stop the control of the converter before the first and second protection relays are opened and controlled to be disconnected from the system. After opening one of the first and second protection relays first, a time difference is provided to open the other, and after opening the one protection relay, the other protection relay is opened. A power conditioner characterized in that if the detected value of the DC link voltage detecting means does not become lower than a predetermined voltage until then, it is determined that the disconnection operation is abnormal. 2. The power conditioner according to claim 1 , wherein the control unit is configured to change the order of opening control of the first and second protection relays for each disconnection operation. . 3. The power conditioner according to claim 1, wherein the inverter is a voltage-type bridge inverter, and when the contact of the protection relay is closed, system power is supplied to the DC link unit via a feedback diode that forms the voltage-type bridge inverter. A power conditioner that is configured to be supplied.

Images