JP6092647B2 - Power conditioner and connection determination method in power conditioner - Google Patents

Description

  The present invention relates to a power conditioner and a method for determining connection of an input power source connected to the power conditioner.

  Conventionally, for example, in Patent Document 1, in a photovoltaic power generation system, a power conditioner that connects a plurality of solar cell arrays in parallel causes MPPT (maximum power point tracking) to independently track the maximum power point for each solar cell array. : Maximum Power Point Tracking) control to improve system power generation efficiency is disclosed.

JP 11-318042 A

  In such a multi-string configuration in which a plurality of input power supplies are connected in parallel, there is a concern that the wiring of the input power supply may be mistakenly connected to the power conditioner during installation. If the input power supply is not correctly connected, the power generation efficiency of the system is lowered because the MPPT control process cannot be converged to the maximum power point. However, since a certain amount of generated power can be obtained, it is difficult to notice an erroneous connection.

  Therefore, the objective of this invention made | formed in view of this situation is providing the power conditioner and the connection determination method which can determine the connection state of an input power supply in the power generation system of a multistring structure.

The power conditioner according to the present invention for solving the above problems is as follows.
A plurality of DC / DC converters to which a plurality of input power sources are respectively connected;
A plurality of direct current detection units respectively corresponding to the plurality of DC / DC converters;
A connection determination unit for determining a connection state of an input power source with respect to the plurality of DC / DC converters based on a direct current measured by the plurality of direct current detection units,
The plurality of DC / DC converters are configured to be independently switchable.

Furthermore, in the power conditioner according to the present invention,
A control unit that operates each of the plurality of DC / DC converters sequentially and independently is provided.

In addition, a connection determination method according to the present invention that solves the above problem is as follows.
A power conditioner connection determination method comprising: a plurality of DC / DC converters to which a plurality of input power supplies are respectively connected; and a plurality of DC current detection units respectively corresponding to the plurality of DC / DC converters.
Independently operating any one of the plurality of DC / DC converters;
Measuring a direct current by the direct current detector corresponding to the operated DC / DC converter;
Determining the connection state of the input power supply to the DC / DC converter based on the measured direct current value;
It is characterized by including.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to determine the connection state of the input power supply with respect to a power conditioner in the power generation system of a multistring structure.

It is a circuit diagram which shows the structural example of the power conditioner by one Embodiment of this invention. It is a block diagram which shows the function of the control part in the power conditioner by one Embodiment of this invention. It is a figure which shows the example which misconnected the input power supply to the power conditioner by one Embodiment of this invention. It is a figure which shows the example which misconnected the input power supply to the power conditioner by one Embodiment of this invention. It is a flowchart which shows the connection determination process by the power conditioner by one Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a circuit configuration example of a main part of a power conditioner 1 according to an embodiment of the present invention. As shown in FIG. 1, the power conditioner 1 includes a plurality of DC noise filters 100, a plurality of DC voltage detectors 101, a plurality of DC current detectors 102, and a plurality of input power supplies via a plurality of input terminals. 2, a plurality of DC / DC converters 103, an inverter 104, an AC voltage detection unit 105, an AC current detection unit 106, an AC noise filter 107, and an interconnection relay 108 that connects the AC system 3, An operation unit 109, a notification unit 110, and a control unit 111 are provided. Moreover, although this embodiment demonstrates the case where the input power supply 2 which can be connected to the power conditioner 1 is three, the number of the input power supplies 2 which can be connected should just be two or more.

  The DC noise filter 100 removes radiation noise and the like from the DC output of the input power supply 2.

  The plurality of DC voltage detection units 101 and the plurality of DC current detection units 102 correspond to the plurality of DC / DC converters 103, respectively, and input DC voltage values and input DC current values of the corresponding DC / DC converters 103 are respectively determined. Measure and input to the control unit 111.

  Each DC / DC converter 103 performs voltage conversion on the input from the input power supply 2 connected thereto. The DC / DC converter 103 of FIG. 1 is a general non-consecutive circuit composed of a choke coil, a capacitor, a diode for preventing a reverse current from the capacitor, a semiconductor switching element, and a freewheel diode connected in parallel to the semiconductor switching element. Although an isolated boost converter is shown, the specific circuit configuration is not limited to this.

  The inverter 104 converts the DC power output from each DC / DC converter 103 into AC and supplies the AC power to the AC system 3. The inverter 104 in FIG. 1 shows a general single-phase inverter composed of four semiconductor switching elements constituting a full-bridge circuit and a reactor inserted in each phase of a single phase. It is not limited to this.

  The AC voltage detection unit 105 and the AC current detection unit 106 measure an AC voltage and an AC current between the inverter 104 and the interconnection relay 108 and input them to the control unit 111.

  The AC noise filter 107 removes high frequency noise and the like from the AC output of the inverter 104.

  The interconnection relay 108 is opened when the failure of the power conditioner 1 itself occurs, or when the user stops the driving operation, and disconnects the AC system 3.

  The operation unit 109 receives an operation of the operator with respect to the power conditioner 1 and inputs the operation to the control unit 111. For example, based on an input from the operator via the operation unit 109, the control unit 111 starts / stops the normal operation of the power conditioner 1 or performs a connection determination process for the input power source 2 with respect to the power conditioner 1. The connection determination process will be described in detail with reference to FIG.

  The notification unit 110 notifies the operator of the DC current measurement value measured by the DC current detection unit 102 and / or the connection determination result of the input power source 2. The notification unit 110 can be, for example, a 7-segment display panel using a speaker or a light emitting element such as an LED.

  The control unit 111 controls the DC / DC converter 103, the inverter 104, the interconnection relay 108, and the notification unit 110, and controls the operation of the power conditioner 1. In addition, the control unit 111 independently controls the operations of the plurality of DC / DC converters 103 in the connection determination process of the input power supply 2 to the power conditioner 1. Details of these controls will be described in detail with reference to FIG.

  FIG. 2 is a block diagram illustrating functions of the control unit 111 in FIG. The control unit 111 includes a sensor value acquisition unit 112, a converter control unit 113, an inverter control unit 114, an interconnection / system control unit 115, an operation reception unit 116, a notification control unit 117, and a connection determination unit 118. Is provided.

  The sensor value acquisition unit 112 acquires a DC voltage measurement value and a DC current measurement value from the DC voltage detection unit 101 and the DC current detection unit 102, respectively. The sensor value acquisition unit 112 acquires an AC voltage measurement value and an AC current measurement value from the AC voltage detection unit 105 and the AC current detection unit 106, respectively.

  The converter control unit 113 performs MPPT control on the DC / DC converter 103 based on the DC voltage measurement value and the DC current measurement value acquired by the sensor value acquisition unit 112 in the normal operation of the power conditioner 1.

  Further, in the connection determination process of the input power supply 2 to the power conditioner 1, the converter control unit 113 operates one DC / DC converter 103 that determines the connection state independently, and stops the other DC / DC converters 103. (Semiconductor switching element is turned OFF). Here, which DC / DC converter 103 is to be determined for the connection state may be determined based on an operator input received by an operation receiving unit 116 described later, or may be determined by the converter control unit 113. Good.

  The inverter control unit 114 controls the output of the inverter 104 based on the AC voltage measurement value and the AC current measurement value acquired by the sensor value acquisition unit 112.

  The interconnection / system control unit 115 opens the interconnection relay 108 when the failure of the power conditioner 1 itself occurs, or when the operation reception unit 116 receives an operation stop input from the operator. Disconnect.

  The operation receiving unit 116 receives an operator input from the operation unit 109. Based on this input, the control unit 111 starts / stops the normal operation of the power conditioner 1 or performs a connection determination process for the input power source 2 with respect to the power conditioner 1.

  The notification control unit 117 controls the notification unit 110 so that the DC current measurement value acquired by the sensor value acquisition unit 112 and / or the connection determination result of the input power source 2 acquired from the connection determination unit 118 are sent to the operator. Notice.

  The connection determination unit 118 determines whether or not the DC current measurement value acquired by the sensor value acquisition unit 112 is normal in the connection determination process of the input power supply 2 to the power conditioner 1. When the DC current measurement value is normal, the connection determination unit 118 determines that the input power supply 2 is correctly connected to the DC / DC converter 103 that is operating independently. On the other hand, when the DC current measurement value is abnormal, the connection determination unit 118 determines that the input power source 2 is not correctly connected to the DC / DC converter 103 that is operating alone. Here, the DC current measurement value being abnormal means that the DC current measurement value is not more than a predetermined threshold value. The principle of determining the connection state will be described in detail with reference to FIGS.

  Further, the connection determination unit 118 notifies the operator of the connection determination result of the input power source 2 via the notification control unit 117 and the notification unit 110.

  With reference to FIG. 3 and FIG. 4, the principle of determination of a connection state according to an embodiment of the present invention will be described. FIG. 3 shows an example in which the N terminal of the first input power supply 2-1 and the N terminal of the second input power supply 2-2 are erroneously connected in reverse. The current path 4 (4-1, 4-2) is a current path of the input power source 2 (2-1, 2-2) connected to the power conditioner 1. The first current path 4-1 passes through the choke coil and the diode of the first DC / DC converter 103-1 from the P terminal of the first input power source 2-1, and passes through the point A in FIG. 104, passes through the second DC current detection unit 102-2, and returns to the N terminal of the first input power source 2-1. The second current path 4-2 passes through the choke coil and the diode of the second DC / DC converter 103-2 from the P terminal of the second input power source 2-2, and passes through the point A in FIG. 104, passes through the first DC current detector 102-1, and returns to the N terminal of the second input power source 2-2. In FIG. 3, the third current path 4-3 corresponding to the third input power supply 2-3 is not shown.

  First, the converter control unit 113 operates the first DC / DC converter 103-1 alone, and stops the second DC / DC converter 103-2 and the third DC / DC converter 103-3. Here, in general, the intermediate link voltage (the voltage at point A in FIG. 3) is set higher than the open circuit voltage of the input power supply 2. Therefore, a current flows from the first input power source 2-1 connected to the operated first DC / DC converter 103-1, but the stopped DC / DC converters 103-2 and 103-3. No current flows from the input power supplies 2-2 and 2-3 connected to the.

  That is, at a voltage value equal to or higher than the start voltage that can be generated, no current flows through the current path 4-2, and the DC current measurement value of the first DC current detection unit 102-1 is 0A.

  In FIG. 4, the P terminal of the input power supply 2 is mistakenly used as the N terminal of the first DC / DC converter 103-1, and the N terminal of the input power supply 2 is mistakenly used as the P terminal of the second DC / DC converter 103-2. An example of connection is shown. The current path 4 passes from the P terminal of the input power supply 2 through the first DC current detection unit 102-1, passes through the free wheel diode and the choke coil of the second DC / DC converter 103-2, and enters the input power supply. Return to N terminal of 2. Therefore, a current flows through the first DC current detection unit 102-1 in the direction opposite to that during normal connection. Therefore, the direct current measurement value of the first direct current detection unit 102-1 shows a negative value.

  As described above, when the DC current measurement value of the first DC current detection unit 102-1 corresponding to the operated first DC / DC converter 103-1 is 0 A or less, that is, the DC current measurement value is a predetermined threshold value. When it is below, it can be determined that the input power supply 2 is erroneously connected to the first DC / DC converter 103-1. This threshold value is, for example, a value that can be determined to be 0 A within the measurement error range. The determination as to whether or not the DC current measurement value is abnormal may be made by an operator who is notified of the DC current measurement value via the notification unit 110, for example, or the connection determination unit 118 may determine a predetermined threshold value. It may be performed automatically based on the comparison.

  FIG. 5 is a flowchart showing connection determination processing of the input power supply 2 to the power conditioner 1 according to the embodiment of the present invention. The self-diagnosis function of the connection state will be described with reference to FIG. The self-diagnosis function can be activated, for example, via the operation unit 109. First, the control unit 111 stops the normal operation of the power conditioner 1 (step S10).

  Next, converter control unit 113 sets variable n to 1 as an initial setting (step S11). Note that n is an integer value that takes a value from 1 to N, and N represents the number of input power sources 2 connected to the power conditioner 1.

  Subsequently, the converter control unit 113 operates the nth DC / DC converter 103-n (step S12). Then, the converter control unit 113 stops each DC / DC converter 103 other than the nth DC / DC converter 103-n (step S13).

  Next, the sensor value acquisition unit 112 acquires a direct current measurement value from the nth direct current detection unit 102-n (step S14).

  Next, the connection determination unit 118 determines whether or not the DC current measurement value acquired by the sensor value acquisition unit 112 is normal based on a comparison with a predetermined threshold set in advance (step S15). When the DC current measurement value is normal, that is, when the measured value is larger than the predetermined threshold, the process proceeds to step S16.

  Next, converter control unit 113 increments the value of n and determines whether or not the value of n exceeds N (step S16). If N is not exceeded, the process returns to step S12. If N is exceeded, the process proceeds to step S17.

  When N is exceeded in step S16, the connection determination unit 118 determines that all the input power sources 2 are normally connected to all the DC / DC converters 103 (step S17).

  Next, the notification control unit 117 notifies the operator of the normal connection via the notification unit 110 (step S18).

  Next, the control unit 111 resumes normal operation of the power conditioner 1 (step S19).

  On the other hand, when the measured direct current value is abnormal in step S15, that is, when the measured value is equal to or less than the predetermined threshold value, the connection determination unit 118 connects the input power source 2 to the nth DC / DC converter 103-n correctly. It determines with not having (step S20).

  Next, the notification control unit 117 notifies the operator via the notification unit 110 that the connection is incorrect (step S21).

  As described above, according to the present invention, the control unit 111 operates one of the plurality of DC / DC converters 103 alone and stops the other DC / DC converters 103. When the direct current measurement value of the direct current detection unit 102 corresponding to the operated DC / DC converter 103 is abnormal, it is determined that the input power source 2 is not correctly connected. As a result, in the power generation system having a multi-string configuration, it is possible to determine the connection state of the input power source 2 to the power conditioner 1.

  Although the present invention has been described based on the drawings, it should be noted that those skilled in the art can easily make various modifications and corrections based on the present disclosure. For example, in the above-described embodiment, the control unit 111 determines the connection of the input power supply 2 in the connection determination process, but the operator manually operates one DC / DC converter 103 alone. May be. In this case, it is possible for the operator to determine the connection of the input power source 2 from the input direct current corresponding to the operated DC / DC converter 103.

DESCRIPTION OF SYMBOLS 1 Power conditioner 100 DC noise filter 101 DC voltage detection part 102 DC current detection part 103 DC / DC converter 104 Inverter 105 AC voltage detection part 106 AC current detection part 107 AC noise filter 108 Linkage relay 109 Operation part 110 Notification part 111 Control unit 112 Sensor value acquisition unit 113 Converter control unit 114 Inverter control unit 115 Interconnection / system control unit 116 Operation reception unit 117 Notification control unit 118 Connection determination unit 2 Input power source 3 AC system

Claims (3)

A plurality of DC / DC converters to which a plurality of input power sources are respectively connected;
A plurality of direct current detection units respectively corresponding to the plurality of DC / DC converters;
A connection determination unit for determining a connection state of an input power source with respect to the plurality of DC / DC converters based on a direct current measured by the plurality of direct current detection units,
The plurality of DC / DC converters are configured to be capable of switching operation independently. Characterized in that it comprises a control unit for operating the respective sequence alone for the plurality of DC / DC converters all, power conditioner according to claim 1. A power conditioner connection determination method comprising: a plurality of DC / DC converters to which a plurality of input power supplies are respectively connected; and a plurality of DC current detection units respectively corresponding to the plurality of DC / DC converters.
Independently operating any one of the plurality of DC / DC converters;
Measuring a direct current by the direct current detector corresponding to the operated DC / DC converter;
Determining the connection state of the input power supply to the DC / DC converter based on the measured direct current value;
The connection determination method characterized by including.

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