JP6644853B1 - Photovoltaic power generation equipment insulation monitoring device and photovoltaic power generation equipment insulation monitoring method - Google Patents

Abstract

The present invention provides an insulation monitoring device for a photovoltaic power generation facility and a method for monitoring the insulation of a photovoltaic power generation facility capable of measuring an insulation resistance before and after a power conditioner by measuring a voltage between resistors. When the voltage seen from the ground to a P-phase terminal (4p) is Vrp during interconnection operation via a power conditioner (7), if the sign of the voltage value (Vrp) is negative, the voltage on the AC side of the power conditioner (7) is reduced. It is determined that the insulation resistance has decreased, and if the sign of the voltage value Vrp is positive, it is determined that the insulation resistance on the DC side of the power conditioner 7 has decreased. [Selection diagram] Fig. 2

Description

  The present invention relates to an insulation monitoring device for a photovoltaic power generation facility and an insulation apparatus for a photovoltaic power generation facility capable of measuring the insulation resistance before and after the power conditioner (or diagnosis: hereinafter referred to as “measurement”) in a power generation state. It concerns monitoring methods.

  BACKGROUND ART Conventionally, a photovoltaic power generation facility including a photovoltaic cell panel, a relay terminal box to which a DC voltage output from the photovoltaic cell panel is input, and a power conditioner has been proposed.

  In such photovoltaic power generation facilities, if a leakage occurs in the DC circuit from the photovoltaic panel to the power conditioner, normal power generation cannot be performed, and a leakage fire or an electric shock accident may occur. A resistance measurement needs to be performed.

  As described in Patent Literature 1, the present applicant has previously described an insulation resistance measuring apparatus for a solar power generation facility and an insulation resistance measurement for a solar power generation facility, which can measure the insulation resistance in a power generation state. Suggest a way.

Japanese Patent No. 5603444

  In the insulation resistance measuring device and the insulation resistance measuring method of the photovoltaic power generation equipment described above, without removing the surge absorber and covering, without short-circuiting, the DC circuit in the power generation state is not changed. Insulation resistance can be measured. Therefore, the insulation resistance can be easily measured without danger, which contributes to the spread of solar power generation equipment in the future.

  As shown in FIG. 1, the insulation monitoring device for a photovoltaic power generation facility can perform insulation diagnosis during the interconnection operation between the commercial side (the right side in FIG. 1) and the insulation transformer 8. When the power conditioner (hereinafter, referred to as “PCS”) 7 is of a non-insulated type, a commercial frequency insulating type is used in which interconnection operation is performed via an externally installed insulating transformer (with a contact prevention plate) 8.

  In the insulation diagnosis by the monitoring device in the commercial frequency insulation method, the insulation monitoring range is from the solar panel 1 to the primary side of the insulation transformer 8, and includes the AC side (the right side in FIG. 1) of the PCS 7.

  In the insulation diagnosis during the interconnection operation, when insulation is reduced, it is determined whether the insulation is reduced on the DC side (the left side in FIG. 1) of the PCS 7 or the AC side of the PCS 7 is reduced. desired.

  Therefore, the present invention is proposed in view of the above-described circumstances, and measures a voltage between resistors in a power generation state without requiring a treatment before measurement such as an insulation resistance meter. Accordingly, an object of the present invention is to provide an insulation monitoring device for a photovoltaic power generation facility and a method for monitoring the insulation of a photovoltaic power generation facility, which can measure the insulation resistance before and after the power conditioner.

  The present invention has been proposed to solve the above problems, and an insulation monitoring device for a photovoltaic power generation facility according to a first invention (the invention according to claim 1) has the following configuration. is there.

[Configuration 1]
A voltage output from a photovoltaic panel to which a plurality of photovoltaic modules are connected is input, a generated voltage between the P-phase and the N-phase, a ground voltage via a measuring instrument resistor at the P-phase terminal, and an N-phase terminal A measuring means for switching and measuring a ground voltage via a measuring instrument resistance, and a control means for controlling the measuring means and performing an operation on a measurement result by the measuring means, and interconnecting via a power conditioner. During operation, when the voltage value of the voltage when the P-phase terminal is viewed from the ground is defined as a voltage value Vrp, if the sign of the voltage value Vrp is minus, it is determined that the insulation resistance on the AC side of the power conditioner has decreased. If the sign of the voltage value Vrp is positive, it is determined that the insulation resistance on the N-phase side on the DC side of the power conditioner is reduced.

The insulation monitoring method for a photovoltaic power generation facility according to the second invention (the invention according to claim 2) has the following configuration.
[Configuration 2]
A solar cell panel having a plurality of solar cell modules connected and having a P-side terminal and an N-side terminal; a P-phase terminal connected to the P-side terminal; and an N-phase terminal connected to the N-side terminal. And a power conditioner in which a voltage output from the solar cell panel is input from the P-side terminal to the P-phase terminal and a power conditioner is input from the N-side terminal to the N-phase terminal. In the insulation monitoring method, during the interconnection operation via a power conditioner, the voltage value Vrp of the voltage when the P-phase terminal is viewed from the ground is measured, and if the sign of the voltage value Vrp is minus, the power value is measured. determines that reduction in the insulation resistance of the AC side of the conditioner, and wherein the sign of the voltage value Vrp is determined to decrease in the insulation resistance of the N-phase side of the DC side of the power conditioner if positive Is shall.

In the insulation monitoring device for a photovoltaic power generation facility according to the first invention (the invention according to claim 1), by having the above-described configuration 1, during the interconnection operation via the power conditioner, the P-phase determine the voltage value of the voltage viewed terminals sign of the voltage Vrp with a decrease in the insulation resistance of the AC side of the power conditioner if negative, DC of the power conditioner if code plus the voltage Vrp It can be determined that the insulation resistance on the side has decreased.

The insulation monitoring method for a photovoltaic power generation facility according to the second invention (the invention according to claim 2) has the above configuration 2, and thus, during the interconnection operation via the power conditioner, the P-phase insulating sign of the voltage Vrp of the voltage viewed terminal determines that reduction in the insulation resistance of the AC side of the power conditioner if negative, the sign of the voltage value Vrp is the DC side of the power conditioner if positive It can be determined that the resistance has decreased.

  In other words, the present invention enables the measurement of the insulation resistance before and after the power conditioner by measuring the voltage between the resistances in the power generation state without requiring a pre-measurement treatment such as an insulation resistance meter. It is possible to provide an insulation monitoring device for a photovoltaic power generation facility and a method for monitoring the insulation of a photovoltaic power generation facility.

It is a block diagram showing composition of an insulation monitoring device of a photovoltaic power generation facility and a photovoltaic power generation facility according to the present invention. It is a circuit diagram (P phase measurement) showing composition of an insulation monitoring device of a photovoltaic power generation facility and a photovoltaic power generation facility according to the present invention. It is a circuit diagram (N-phase measurement) showing composition of an insulation monitoring device of a photovoltaic power generation facility and a photovoltaic power generation facility according to the present invention. It is a circuit diagram (there is no AC side insulation fall) which shows the composition of the insulation monitoring device of the photovoltaic power generation facility and the photovoltaic power generation facility concerning the present invention. It is a flowchart which shows the procedure (when it is in the measurement mode) of the insulation resistance measurement by the insulation monitoring method of the photovoltaic power generation equipment which concerns on this invention. It is a flowchart (continuation of FIG. 5) which shows the procedure of the insulation resistance measurement by the insulation monitoring method of the photovoltaic power generation equipment which concerns on this invention. It is a flowchart which shows the procedure of the insulation resistance measurement by the insulation monitoring method of the solar power generation equipment which concerns on this invention (when measuring insulation resistance by a logger mode). It is a top view which shows the structural example (9 series x 3 parallel) of a solar cell panel.

  Hereinafter, embodiments of an insulation monitoring device for a photovoltaic power generation facility and an insulation monitoring method for a photovoltaic power generation facility according to the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of an insulation monitoring device for a photovoltaic power generation facility and a photovoltaic power generation facility according to the present invention.

  The insulation monitoring device for a photovoltaic power plant according to the present invention executes the method for monitoring the insulation of a photovoltaic power plant according to the present invention. As shown in FIG. 1, a photovoltaic power generation facility to which the insulation monitoring device for a photovoltaic power generation facility according to the present invention is connected includes a photovoltaic panel 1 to which a plurality of photovoltaic modules are connected, and a photovoltaic panel 1. And a relay terminal 2 to which the output voltage is input.

  The P-side (+ side) terminal 1p of the solar cell panel 1 is connected to the P-phase terminal of the PCS 7 via the relay terminal 2, and the N-side (-side) terminal 1n of the solar cell panel 1 is connected via the relay terminal 2. , PCS7 are connected to the N-phase terminal. The PCS 7 may have a built-in MCCB (Molded Case Circuit Breaker).

  And in the insulation monitoring device of the photovoltaic power generation facility according to the present invention, the voltage between the P-phase and the N-phase on the power supply (photovoltaic panel 1) side (the generated voltage of the photovoltaic panel 1) (V); A measuring unit serving as measuring means for measuring a ground voltage (Vrp) of the P-phase terminal 4p on the power supply (photovoltaic panel 1) side and a ground voltage (Vrn) of the N-phase terminal 4n on the power supply (photovoltaic panel 1) side. 5 is provided.

  FIG. 2 is a circuit diagram (P-phase measurement) showing the configuration of the insulation monitoring device for a photovoltaic power generation facility and the photovoltaic power generation facility according to the present invention.

  FIG. 2 shows a state in which the measuring unit 5 has one end of the measuring device resistor connected to the P-phase terminal 4p, and the other end of the measuring device resistor R is grounded. The measuring unit 5 is a voltage measuring unit that measures the P-phase and N-phase voltages to the ground (PE voltage Vrp and NE voltage Vrn) and the P-phase voltage (V). have. The voltage measurement unit has a voltage divider connected to the P-phase terminal 4p and the N-phase terminal 4n, and an AMP for amplifying the output of the voltage divider, and the output of the AMP is input to the switch circuit SW. On the other hand, the voltage between both ends of the measuring device resistance is amplified by another AMP and input to the switch circuit SW. The output of the switch circuit SW is converted into a digital signal in the A / D converter and input to the signal processing circuit CPU. A display device LCD is connected to the signal processing circuit CPU.

  The measurement results (the generated voltage value (V) of the solar cell panel 1 and the voltage values (Vrp, Vrn) between both ends of the measuring device resistance) in the measuring unit 5 are displayed on the display device LCD by the signal processing circuit CPU.

  When the MCCB is built in the PCS 7, the measuring unit 5 can measure the voltage between the P-phase and the N-phase on the power supply side without opening the MCCB in the power conditioner and the P-phase terminal. The ground voltage via the measuring resistor R and the ground voltage via the measuring resistor R at the N-phase terminal are measured.

[Insulation diagnosis of AC side of PCS7]
As shown in Table 1, for example, in the measurement in the measurement mode, when the insulation on the DC side of the PCS 7 is reduced, the voltage value Vrp between the P and E of the measuring instrument resistance shows a plus sign. When insulation is reduced in each phase (U, V, W) on the AC side up to the transformer 8, the PE voltage value Vrp indicates a minus sign.

  Therefore, from the identification of the sign of Vrp, it is possible to determine whether the DCS or the AC side of the PCS 7 is a section where the insulation is reduced.

  As shown in FIG. 2, the non-insulated PCS 7 has a chopper circuit that boosts the low DC output voltage from the solar cell panel in order to enable the inverter operation even when the output voltage decreases. When measuring Vrp, which is the voltage between the P and E of the resistance of the measuring instrument, the loop current originating from the boosted voltage by the boosting chopper causes the loop current originating from the ground of the measuring instrument resistance, regardless of the insulation reduction in any of the AC phases. Power is applied to the P phase. Therefore, Vrp indicates a minus sign.

  FIG. 4 is a circuit diagram (with no AC-side insulation reduction) showing the configuration of the photovoltaic power generation facility insulation monitoring device and the photovoltaic power generation facility according to the present invention.

  As shown in FIG. 4, when the insulation of the DC side of the PCS 7 is lowered, when the changeover switch of the measuring device resistance is set to the PE side, the leakage current that flows through the measuring device resistance depending on the insulation lowers from the P phase. Energize to ground. Therefore, Vrp, which is the voltage between the resistances of the measuring devices, indicates a plus sign.

  As described above, by distinguishing the sign of Vrp, it is possible to distinguish whether the insulation reduction is the DC side or the AC side of the PCS 7.

If insulation is reduced on the AC side of the PCS 7, the insulation resistance value can be calculated as follows.

As shown in Table 1, in the interconnection operation of the PCS7, even if any one of the phases on the AC side causes insulation deterioration, the resistance between the measuring instrument resistances of the monitoring device is between PE and NE. Vrp and Vrn are detected as voltages dependent on the leakage current. If the changeover switch of the measuring instrument resistance is set between P and E, the detection of Vrp occurs as shown in FIG. 2, originating from 160V (V2) which is the boosted voltage by the boosting chopper. Table 2 below shows the DC voltage generated in each DC circuit during the measurement. In particular, the generated voltage is 180 V (for example) between PN. Table 3 below shows the DC voltage generated in the AC circuit during the measurement. When the resistance of the measuring instrument is set to the P-phase side, each phase (U, V, W) on the AC side is connected to the ground. The voltage is 160 V (for example), and when it is on the N-phase side, it is 340 V which is an added value of the boosted voltage by the boost chopper and the generated voltage.

  FIG. 3 is a circuit diagram (N-phase measurement) showing the configuration of the insulation monitoring device for a photovoltaic power generation facility and the photovoltaic power generation facility according to the present invention.

When the changeover switch of the measuring instrument resistance is set to the NE side, the leakage current flowing through the measuring instrument resistance when the insulation on the AC side of the PCS 7 is reduced is the sum of the generated voltage (V1) and the boosted voltage (V2) by the boosting chopper. It originates from the voltage (V1 + V2).
The above relationship can be expressed by the following equation. Equation (1) shown below is a measured value based on the circuit diagram shown in FIG. 2, and equation (2) is a measured value based on the circuit diagram shown in FIG.
Vrp = R · V2 / (Rac + R) (1)
Vrn = R · (V1 + V2) / (Rac + R) (2)
(∵Vrp, Vrn: measured value of the monitoring device, generated voltage V1: measured value of the monitoring device, measuring device resistance R: known, boosted voltage by boosting chopper V2: unknown, insulation resistance Rac of PCS7 AC side: unknown)
When Rac is obtained from the equations (1) and (2), the following equation (3) is obtained.
The insulation resistance value on the AC side of the PCS 7 can be calculated from the equation (3) using the measured value of the monitoring device as a parameter.
Rac = R · (V1 + Vrp−Vrn) / (Vrn−Vrp) (3)
For example, NO. As shown in FIG. 6, when the simulated insulation resistance value is 1.01 MΩ,
Rac = 5000 · (177.8 + 0.894-1.76) / (1.76-0.894) = 1.02 MΩ

  As described above, as the determination of the section where the insulation has been reduced, the DC side and the AC side of the PCS 7 are re-measured in the above measurement mode, and if Vrp is given a minus sign, the insulation reduction of the PCS 7 on the AC side can be determined. In addition, the insulation resistance value can be calculated. When a minus sign is attached to Vrp as a display screen of the measurement unit 5, the AC side of the PCS 7 and the calculated insulation resistance value can be displayed on the screen.

  Further, in the measurement mode, it is possible to specify the insulation reduction section.

  The specification of the insulation reduction section on the AC side of the PCS 7 is performed during PCS operation (interconnection operation).

  When the measuring section 5 detects a decrease in insulation on the AC side of the PCS 7, the Vrp value of the voltage between the resistances of the measuring instruments has a minus sign, so that a decrease in insulation on the AC side of the PCS 7 can be recognized. The insulation resistance value on the AC side of the PCS 7 is measured in the measurement mode of the measurement unit 5, and the voltages between the measurement device resistances (Vrp, Vrn), the generated voltage V1, and the measurement device resistance are calculated as parameters. When the interconnection of the PCS 7 is stopped, such as when it is raining, the measuring unit 5 does not detect a decrease in insulation on the AC side of the PCS 7.

[Insulation diagnosis on the DC side of PCS7]
In the measurement mode of the insulation monitoring device of the photovoltaic power generation facility, the P-phase insulation resistance in the DC circuit from the photovoltaic cell panel 1 to the MCCB incorporated in the PCS 7 is reduced based on the measurement result of the measurement unit 5. , The decrease in the insulation resistance of the N-phase in the DC circuit is detected separately, or between the P-phase and the N-phase or between the solar cell modules, the P-phase, the N-phase, and the solar cell module in the DC circuit. And a decrease in the insulation resistance at a plurality of locations including the above. This measurement can be performed with the DC circuit live.

  Note that the insulation diagnosis on the DC side is a content that has been already proposed by the present applicant in Patent Document 1 (Japanese Patent No. 5603444).

  When the insulation resistance decreases in the DC circuit from the solar cell panel 1 to the PCS 7, a voltage Vr is generated between the P-phase terminal 4p or N-phase terminal 4n and the ground via the measuring instrument resistance R. Therefore, the insulation resistance of the DC circuit can be known by measuring the voltage Vr to the ground and the generated voltage V of the solar cell panel 1. The generated voltage V of the photovoltaic cell panel 1 varies depending on the amount of light applied to the photovoltaic cell panel 1 and is measured as needed.

  In this photovoltaic power generation system, (1) P-phase insulation decrease, (2) N-phase insulation decrease, (3) both-phase insulation decrease, or P-phase, N-phase, and solar cell module There is a possibility that either of the insulation loss at a plurality of locations including (4) insulation deterioration between the solar cell modules may occur, and it is necessary to know the occurrence of the ground voltage via the P-phase or N-phase measuring device resistance R. Thus, these can be distinguished and detected.

In this photovoltaic power generation facility, when a leakage occurs due to a decrease in the insulation of the P-phase, when the changeover switch 6 is switched to the P-phase terminal 4p, no voltage is generated across the measuring resistor R. When the switch 6 is switched to the N-phase terminal 4n, a voltage Vnr is generated at both ends of the measuring resistor R. When only the P-phase is insulated, the following holds.
Rp = R [｛(V ₁ −Vpr) / Vnr｝ −1] (however, Vpr ≒ 0)

In this photovoltaic power generation facility, when a leakage occurs due to a decrease in insulation of the N-phase, when the changeover switch 6 is switched to the P-phase terminal 4p, a voltage Vpr is generated across the measuring resistor R. When the changeover switch 6 is switched to the N-phase terminal 4n, no voltage is generated across the measuring instrument resistor R. When only the N-phase is insulated, the following holds.
Rn = R _{[{(V 2 -Vnr) / Vpr} } -1 ] ... (although, Vnr ≒ 0)

In this photovoltaic power generation facility, when a leakage occurs due to insulation deterioration at both P-phase and N-phase, or at a plurality of locations including between the P-phase, N-phase and the solar cell module, the changeover switch 6 is set to P-phase. When switching to the phase terminal 4p, a voltage Vpr is generated across the measuring instrument resistor R. When the switch 6 is switched to the N-phase terminal 4n, a voltage Vnr is generated at both ends of the measuring resistor R. If the insulation is reduced at a plurality of locations including both the P-phase and the N-phase, or between the P-phase, the N-phase and the solar cell module, the following holds.
Rp = R _{[{(V 3 -Vpr) / Vnr} } -1 ]
Rn = R _{[{(V 3 -Vnr) / Vpr} } -1 ]
Rpn = (Rgp · Rgn) / (Rgp + Rgn) = R _{[{V 3 / (Vpr + Vnr} )} - 1 ]

  In this photovoltaic power generation facility, when a leakage occurs due to a decrease in insulation between the solar cell modules, when the changeover switch 6 is switched to the P-phase terminal 4p, a voltage Vpr is generated across the measuring resistor R. . When the switch 6 is switched to the N-phase terminal 4n, a voltage Vnr is generated at both ends of the measuring resistor R.

That is, when the measuring instrument voltages Vpr and Vnr are generated in both the P-phase and the N-phase, insulation is reduced in both the P-phase and the N-phase, or the P-phase, the N-phase, and the solar cell This is the case where the insulation is reduced at a plurality of locations including between the modules, or the insulation is reduced between the solar cell modules. If the insulation decreases between the solar cell modules, the following holds.
Rpn = R _{[{V 4 / (Vpr + Vnr} )} - 1 ]

  As described above, in the insulation monitoring device for a photovoltaic power generation facility according to the present invention, by measuring the voltage Vr across the measuring device resistance R and the generated voltage V of the photovoltaic cell panel 1, it is possible to know the insulation resistance Rpn. Can be. Further, the occurrence of the voltage Vr across the measuring instrument resistor R (P-phase generation, N-phase generation, both P-phase and N-phase generation) and the number of series solar cell panel modules are known, so that insulation is reduced. The section can be determined.

〔flowchart〕
FIG. 5 is a flowchart showing a procedure for measuring insulation resistance by the method for monitoring insulation of a photovoltaic power generation facility according to the present invention. FIG. 6 is a flowchart (continuation of FIG. 5) showing the procedure of measuring the insulation resistance by the method for monitoring insulation of a photovoltaic power generation facility according to the present invention.

  To measure the insulation resistance of the photovoltaic power generation facility by executing the method for monitoring the insulation of the photovoltaic power generation facility according to the present invention using the insulation monitoring device for the photovoltaic power generation facility according to the present invention, as shown in FIG. The CPU of the measuring unit 5 proceeds to step st2 when starting the process in step st1, and proceeds to step st3 when the switch of the measuring unit 5 is turned on. In step st3, the measurement device resistance R is automatically measured. In step st4, the generated voltage V of the solar cell panel 1 is measured, and the process proceeds to step st5. In step st5, the changeover switch 6 is switched to the P-phase side to measure the voltage Vrp across the measuring instrument resistor R, and the process proceeds to step st6.

  In step st6, the generated voltage V of the solar cell panel 1 is measured, and the process proceeds to step st7. In step st7, the changeover switch 6 is switched to the N-phase side to measure the voltage Vrn across the measuring resistor R, and the process proceeds to step st8. In step st8, the generated voltage V of the solar cell panel 1 is measured, and the process proceeds to step st9. In step st9, it is determined whether or not the value of the voltage value Vrp is, for example, 50 mV or more. If it is 50 mV or more, the process proceeds to step st10, and if not, the process proceeds to step st15. In step st10, it is determined whether or not the sign of the voltage value Vrp is minus. If it is minus, the process proceeds to step st11. If it is plus, the process proceeds to step st15.

  In step st11, the insulation resistance on the AC side of the PCS 7 is calculated, and the process proceeds to step st12. In step st12, it is determined whether or not this insulation resistance value is less than 20 MΩ. If it is less than 20 MΩ, the process proceeds to step st13. In this step st13, the AC side insulation resistance value Rac of the PCS 7 is displayed on the display device. Display on LCD. On the other hand, if it is determined in step st12 that the resistance value is equal to or greater than 20 MΩ, the process proceeds to step st14, and the fact that OVER (insulation) has occurred is displayed on the display device LCD. In step st15, the calculation of the insulation resistances Rp and Rn on the DC side of the PCS 7 is started. In step st16, the changeover switch 6 is switched to the N-phase side and the P-phase side, and the insulation resistances Rp and Rn are measured. If each of them is 20 MΩ or more, the process proceeds to step st17. Proceed to st18. At step st17, it is displayed that the insulation resistances Rp and Rn are OVER (insulated).

  In step st18, if the insulation resistance Rp is equal to or greater than 20 MΩ and Rn is less than 1 MΩ, the process proceeds to step st19; otherwise, the process proceeds to step st20.

  In step st19, the fact that the insulation resistance Rp is OVER (insulation) and the value of Rn are displayed. In step st20, if the insulation resistance Rp is 20 MΩ or more and Rn is 1 to 19.99 MΩ, the process proceeds to step st21; otherwise, the process proceeds to step st22. At step st21, the fact that the insulation resistance Rp is OVER (insulation) and the value of Rn are displayed. In step st22, if the insulation resistance Rp is less than 1 MΩ and Rn is 20 MΩ or more, the process proceeds to step st23; otherwise, the process proceeds to step st24. In step st23, it is displayed that the value of the insulation resistance Rp and Rn are OVER (insulation). In step st24, if the insulation resistance Rp is 1 to 19.99 MΩ and Rn is 20 MΩ or more, the process proceeds to step st25; otherwise, the process proceeds to step st26 in FIG. At step st25, the value of the insulation resistance Rp and the fact that Rn is OVER (insulation) are displayed.

  In step st26, the display is turned on and off and the input of the number of serial modules is requested, and the process proceeds to step st27. In step st27, the serial number of the input module is received, and the process proceeds to step st28. In step st28, it is determined whether or not the voltage value and the resistance value match, and if they match, the process proceeds to step st29, and if not, the process proceeds to step st32. In step st29, it is determined whether the resistance between the modules is less than 1 MΩ. If it is less than 1 MΩ, the process proceeds to step st30. If not, the process proceeds to step st31. At step st30, it is displayed that the insulation reduction point is between the modules and the resistance value Rpn. In step st31, the fact that the insulation reduction point is between modules and the resistance value Rpn are displayed.

  In step st32, if the insulation resistance Rp is less than 1 MΩ and Rn is less than 1 MΩ, the process proceeds to step st33; otherwise, the process proceeds to step st34. At step st33, the values of the insulation resistances Rp, Rn, Rpn are displayed.

  In step st34, if the insulation resistance Rp is 1 to 19.99 MΩ and Rn is less than 1 MΩ, the process proceeds to step st35; otherwise, the process proceeds to step st36. At step st35, the values of the insulation resistances Rp, Rn, Rpn are displayed.

  In step st36, if the insulation resistance Rp is less than 1 MΩ and Rn is 1 to 19.99 MΩ, the process proceeds to step st37; otherwise, the process proceeds to step st38. At step st37, the values of the insulation resistances Rp, Rn, Rpn are displayed. At step st38, the values of the insulation resistances Rp, Rn, Rpn are displayed.

  FIG. 7 is a flowchart showing the procedure of measuring the insulation resistance by the insulation monitoring method of the photovoltaic power generation equipment according to the present invention (when measuring the insulation resistance in the logger mode).

  In the insulation monitoring device for a photovoltaic power generation facility according to the present invention, the insulation resistance on the AC side of the PCS 7 can be measured not only in the measurement mode but also in a logger mode in which the insulation measurement result is read and displayed (recorded). In the case of the logger mode, as shown in FIG. 7, when the CPU of the measuring unit 5 starts the process in step st41, the process proceeds to step st42, and when the switch of the measuring unit 5 is turned on, the process proceeds to step st43. In step st43, the measurement device resistance R is automatically measured. In step st44, the generated voltage V of the photovoltaic cell panel 1 is measured, and the process proceeds to step st45. In step st45, the changeover switch 6 is switched to the P-phase side to measure the voltage Vrp across the measuring resistor R, and the process proceeds to step st46.

  In step st46, the generated voltage V of the solar cell panel 1 is measured, and the process proceeds to step st47. In step st47, the changeover switch 6 is switched to the N-phase side to measure the voltage Vrn across the measuring instrument resistor R, and the process proceeds to step st48. In step st48, the generated voltage V of the solar cell panel 1 is measured, and the process proceeds to step st49. In step st49, it is determined whether the value of the voltage value Vrp is, for example, 50 mV or more. If it is 50 mV or more, the process proceeds to step st50, and if it is not 50 mV, the process proceeds to step st55. In step st50, it is determined whether or not the sign of the voltage value Vrp is negative. If it is negative, the process proceeds to step st51, and if it is positive, the process proceeds to step st55.

In step st51, the insulation resistance on the AC side of the PCS 7 is calculated, and the process proceeds to step st52. In this step st52, it is determined whether or not the insulation resistance value is less than 10 MΩ, and if it is less than 10 MΩ, the process proceeds to step st53. In this step st53, the insulation resistance value Rac (MΩ) on the AC side of the PCS 7 is displayed on the display device LCD. If the insulation resistance value is 10 MΩ or more, in step st54, OVER (insulation) is displayed on the display device LCD. In step st55, the DC-side insulation resistance Rpn of the PCS 7 is calculated. Next, in step st56, it is determined whether or not the DC-side insulation resistance Rpn of the PCS 7 is less than 10 MΩ. If it is less than 10 MΩ, in step st57, the insulation resistance value Rpn (MΩ) is displayed on the display device LCD. On the other hand, if the insulation resistance Rpn is equal to or more than 10 MΩ, in step st58, the fact that OVER (insulation) has occurred is displayed on the display device LCD.
When there are a plurality of PCSs, the measurement is performed sequentially (repeatedly) for each PCS.
In the above description, first, the order of measuring the insulation resistance in the photovoltaic power generation facility in the measurement mode is described, and then the order of measuring the insulation resistance in the logger mode is described. It is practical to measure in the measurement mode.

  FIG. 8 is a plan view showing a configuration example (9 series × 3 parallel) of the solar cell panel.

  As shown in FIG. 8, the solar cell module 11 is, for example, a solar cell panel 1 including three rows of nine solar cell modules connected in series. In the solar cell panel 1, the solar cell modules 11 connected in series are connected in parallel on the load side of the corresponding disconnector 12. The solar cell module 11 refers to a module in which several tens of solar cells are connected in series. In general, the solar cell module 11 uses a transparent substrate such as glass as a light receiving surface as a support plate, and seals several tens of solar cells with a transparent filling material and a back sheet under the support plate. , And has a structure in which the periphery is sealed by a frame. The solar cells are connected to each other by soldering via an inner connector. Poor connection (disconnection) of the inner connector can occur, but there is no risk of ground fault because the solar cell is sealed. The terminals of the solar cell modules 11 are provided in terminal boxes provided outside the respective solar cell modules 11.

  INDUSTRIAL APPLICABILITY The present invention is applied to an insulation monitoring device for a photovoltaic power generation facility and an insulation monitoring method for a photovoltaic power generation facility, which enable measurement of insulation resistance in a power generation state.

DESCRIPTION OF SYMBOLS 1 Solar cell panel 2 Relay terminal 4p P-phase terminal 4n N-phase terminal 5 Measurement part 6 Changeover switch 7 Power conditioner 8 Insulation transformer 11 Solar module 12 Disconnector

Claims (2)

A voltage output from a photovoltaic panel to which a plurality of photovoltaic modules are connected is input, a power generation voltage between the P-phase and the N-phase, a ground voltage via a measuring instrument resistor at the P-phase terminal, and an N-phase terminal Measuring means for switching and measuring the earth voltage via the measuring instrument resistance of
Control means for controlling the measuring means, and performing an operation on the measurement result by the measuring means,
During the interconnection operation via the power conditioner, when the voltage value of the voltage when the P-phase terminal is viewed from the ground is set to the voltage value Vrp, if the sign of the voltage value Vrp is minus, the AC side of the power conditioner And that if the sign of the voltage value Vrp is positive, it is determined that the insulation resistance on the N-phase side on the DC side of the power conditioner is reduced. apparatus. A solar cell panel to which a plurality of solar cell modules are connected and which has a P-side terminal and an N-side terminal;
It has a P-phase terminal connected to the P-side terminal and an N-phase terminal connected to the N-side terminal, and a voltage output from the solar cell panel is input from the P-side terminal to the P-phase terminal. A power conditioner input from the N-side terminal to the N-phase terminal;
A method for monitoring the insulation of a photovoltaic power plant using
During the interconnection operation via the power conditioner, the voltage value Vrp of the voltage when the P-phase terminal is viewed from the ground is measured, and if the sign of the voltage value Vrp is minus, the insulation resistance on the AC side of the power conditioner is measured. And determining if the sign of the voltage value Vrp is plus, that the insulation resistance on the N-phase side on the DC side of the power conditioner is decreasing.