JP2011176155A - Solar power generation apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an abnormality detection mechanism for detecting a component which generates abnormal heat in a circuit for matching input power from a solar battery string and outputting to a power conditioner, and to provide a control method of the same. <P>SOLUTION: The solar power generation device includes a plurality of solar battery strings 2a, 2b; a collection circuit 3 which collects power from the plurality of solar battery strings 2a, 2b, the collection circuit 3 having wiring members 4, an electronic component connected by the wiring members 4, and a plurality of temperature detection means 3a arranged on a plurality of junctions 4a where the wiring members 4 join, and adjacent to the electronic component; and an abnormality determination means 3b determining an electronic component causing an abnormality according to a result of the temperature detection means 3a. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a solar power generation device.

  A solar power generation device inputs power generated by a solar cell string in which a plurality of solar cell modules are connected in series to a power conditioner that is a power conversion device, and is supplied with power in an appropriate form to a load.

  In general, the load is often an AC device, and the surplus power may be sold in reverse power to the utility company's commercial power system, so the output voltage of the power conditioner is a single-phase two-wire AC 100V Or, it is controlled to synchronize with the AC waveform of the commercial power system at AC 200V.

  In this way, when generating AC power with an output voltage of 100V or more, DC power input to the power conditioner can be efficiently converted if there is an equivalent voltage. For example, seven solar cell modules with an output voltage of 22V are connected in series. Thus, a 154V solar cell string is produced and input to the power conditioner.

  Thus, the number of solar cell strings in series is determined by the input voltage to the inverter, so when installing more solar cell modules, it is common to create the same number of solar cell strings and connect them in parallel As a matter of course, if the number of solar cell modules cannot be made the same, for example, due to a lack of installation area, a device such as a booster circuit that boosts the voltage is used.

  A connection box is arranged between the solar cell string and the power conditioner as a device for collecting power by electrically connecting the outputs of the plurality of solar cell strings thus made in parallel. A plurality of terminal blocks are combined to combine multiple solar cell inputs into a single output to form a current collector circuit, and the high output of the solar cell string is dragged to the low output to lower the output voltage A backflow prevention diode for preventing this is connected to each solar cell string.

  In addition, the longer the transmission distance between the solar cell string, the junction box, and the power conditioner, the more it will be affected by lightning surges, etc., through the transmission line, so overvoltages such as surge absorbers between the positive and negative electrodes of each solar cell string Protective electronic components are arranged.

  As such a connection box, there are one in which two series of different numbers of solar cell strings are connected in parallel (see Patent Document 1), and three systems that are connected in parallel (see Patent Document 2).

  However, when an electronic component is to be connected in this way, it is necessary to make electrical and mechanical contact using a connector such as a terminal block or a crimp terminal.

  For example, in the case of a terminal block, heat is generated due to an increase in contact resistance such as insufficient tightening of screws due to construction mistakes or loosening of screws due to secular change, and this causes problems such as a decrease in the amount of generated power and in the worst case equipment burnout.

In order to detect such an abnormal temperature rise, a temperature sensor such as a thermocouple is preferably arranged on the electronic component to directly detect the temperature rise. For example, at a terminal, the temperature of one electrode is 100 ° C. Even if it rises, the thermal conductivity between adjacent electrodes is small, so a temperature sensor is required for each terminal, and when combined with a sensor for measuring the temperature of the backflow prevention diode, a large number of sensors are required. Since the same number of circuits are required for the measurement, and the number of electronic components and the circuit are complicated, they are generally not used much.

  In view of such a background, a method for detecting abnormal heat generation is not described, but various mounted electronic components are mounted on a printed wiring board, and a temperature change paint containing a temperature indicating material is applied to the front surface of the printed wiring board to change the color change state. A method for detecting the occurrence of an abnormal temperature rise due to a color change by arranging a temperature indicating material on a plurality of electronic components that are described as performing thermal analysis by visual inspection (see Patent Document 3), and temperature A temperature detection seal that separates the temperature sensitive part that changes the brightness after the temperature of the detected part reaches the brightness change temperature and the temperature insensitive part that has no brightness change is provided on the temperature detected part, and the brightness is controlled by the camera. A method of processing a signal by dividing a plurality of pixels (see Patent Document 4) is described.

JP 2004-146791 A JP 2006-012920 A JP-A-6-347341 JP-A-9-15064

  However, in the method using the temperature indicating material of Patent Document 3, it is possible to see a temperature change at a large number of places. However, a separate means for seeing the color change is necessary. Advanced electronic parts such as sensors and judgment circuits are required, resulting in higher costs, and Patent Document 4 shows the temperature sensing of the heat generation part of the electronic parts, It was not possible to identify the location that caused the failure.

  It is an object of the present invention to detect an electronic component in which abnormal heat generation is generated with only the minimum number of temperature detection means in a photovoltaic power generation apparatus, and to perform an appropriate external output.

  The solar power generation device of the present invention is a current collecting circuit for collecting power from a plurality of solar cell strings and the plurality of solar cell strings, and is connected to the wiring material and the wiring material. A current collecting circuit having an electronic component and a plurality of temperature detecting means arranged adjacent to the electronic component and arranged at each of a plurality of merged portions of the wiring material, and an abnormality depending on a result of the temperature detecting means And an abnormality determining means for determining an electronic component as a factor.

According to the solar power generation device of the present invention, a plurality of solar cell strings and a current collecting circuit for collecting electric power from the plurality of solar cell strings, the wiring material being connected by the wiring material And a plurality of temperature detecting means arranged adjacent to each of the plurality of joining portions where the wiring members are joined, and a plurality of temperature detecting means adjacent to the electronic parts, and a result of the temperature detecting means , The abnormality determination means for determining the electronic component that is the cause of the abnormality, it is possible to know in advance the signs of abnormality of each electronic component, the equipment of the entire photovoltaic power generation device by early action Damage can be reduced.

  For example, abnormal heat generation due to construction mistakes such as insufficient tightening of wiring screws in the junction box is detected early, and protective actions such as alarms and circuit interruptions are performed to reduce the decrease or breakage in the generated power of the solar power generation device. it can.

  In addition, for example, even if a screw loosening or a semiconductor leak occurs due to aging deterioration due to long-term use, etc., a local temperature rise caused by this will be detected, and an alarm or other warning will be given at an early stage to generate solar power. Damage to the device can be reduced.

  In addition, since the number of temperature sensors can be reduced and the temperature rise states at a plurality of locations can be organically compared and determined, it is easy to determine the electronic component that is causing the abnormality.

  For example, to understand the organic influence between electronic components by arranging temperature detection means at the junction of wiring materials between electronic components with heating elements such as wiring material between terminal block and diode Therefore, it is possible to determine whether or not the temperature rise of the electronic component is caused by heat generated by the single component.

It is an example of the schematic diagram of a structure of the solar power generation device of this invention. It is an example of the circuit diagram of the connection box of the solar power generation device of this invention. It is an example of the criterion in the abnormality detection means of the solar power generation device of this invention. It is a temperature rise graph when an electric current is sent through the electronic component (diode) in the present invention.

  DESCRIPTION OF EMBODIMENTS Embodiments of a photovoltaic power generation apparatus according to the present invention will be described in detail based on schematic diagrams.

  According to one embodiment of the present invention, there are a plurality of solar cell strings and a current collecting circuit for collecting electric power from the plurality of solar cell strings, the wiring material being connected by the wiring material. A current collecting circuit having an electronic component and a plurality of temperature detecting means arranged adjacent to the electronic component and arranged in each of a plurality of merged portions of the wiring material, and a result of the temperature detecting means, And an abnormality determining means for determining an electronic component that is an abnormality factor.

  In FIG. 1, in the solar cell photovoltaic power generation device 1, an output cable of a solar cell string 2 in which a plurality of solar cells are connected in series is introduced into a current collecting circuit 3 in a connection box, and each output cable is connected via a wiring member 4. In other words, DC power is output to the power conditioner 5 after being connected in parallel, and the input DC power is converted into AC power and supplied to an AC load (not shown).

  FIG. 2 is a wiring diagram of a solar power generation apparatus in which the solar cell strings 2 are connected in parallel by the current collector circuit 3. The current collector circuit 3 includes terminals P1 (positive electrode side terminals) and N1 (negative electrode side terminals) related to the solar cell string 1. ), Terminals P2 (positive terminal) and N2 (negative terminal) related to the solar cell string 2, and DC power obtained by connecting the outputs of the solar cell string 2a and the solar cell string 2b in parallel are output to the power conditioner 5. Terminal PVO (positive electrode side), NVO (negative electrode side), a backflow prevention diode D1 that prevents the current of the solar cell string 2b from flowing into the solar cell string 2a, and the current of the solar cell string 2a flows into the solar cell string 2b And a backflow prevention diode D2.

  In the present embodiment, for example, assuming that the surge absorbers ZNR1 to ZNR4 for lightning surge protection are arranged on the power receiving side of the solar cell strings 2a and 2b, the number of electronic components includes six terminals and a backflow prevention diode. There will be a total of 14 with 2 and 6 surge absorbers.

  If a temperature sensor is provided for each electronic component, 16 temperature sensors are required. According to the present invention, the arrangement of the temperature sensors is, for example, the signal creation units LP1, LP2, LN1, What is necessary is just to arrange | position at 6 places, LN2, LPO, and LDN.

  A thermocouple is generally used as the temperature sensor, but an electronic component whose resistance value changes with temperature, such as a thermistor, may be used as long as the temperature can be converted into a voltage.

  In the current collecting circuit 3 according to the present invention, the temperature detecting means 3a connected to the joining portion 4a of the wiring member 4 in the current collecting circuit 3, and an abnormal electronic component as a result of comparing the temperature information with normal temperature information An abnormality determining means 3b for determining

  Here, the electronic component includes, for example, a backflow prevention diode, a terminal, a surge absorber, and the like, but other electronic components may be used.

  Furthermore, in the present invention, it is preferable that the abnormality determination unit determines a correction value obtained by subtracting a temperature generated by the power from the solar cell string from a measurement value of the temperature detection unit.

  This makes it possible to distinguish between heat generation due to power generation and heat generation due to failure.

  For example, when almost all of the current generated by the solar cell string 2 flows through the backflow prevention diode D1, the loss increases due to the performance deterioration of the backflow prevention diode D1, and the heat generation amount increases.

  However, since the current increases or decreases depending on the power generation state of the solar cell string 2, it is necessary to determine and correct whether the temperature rise is due to a loss due to abnormality or due to an increase in power generation current.

  For example, FIG. 4 is a graph showing the temperature rise of the backflow prevention diodes D1 and D2 when the generated current of each ratio with respect to the rated current flows through the backflow prevention diodes D1 and D2.

  The vertical axis represents the temperature of the electronic component, and% in the graph is the ratio of the generated current to the rated current of the electronic component, for example, 50% if the generated current is 50 A with respect to the rated current of the 100 A electronic component. It shows that.

  The horizontal axis is the passage of time, and the rise and fall of the curve in the graph is determined by the increase and decrease of the generated current.

  Since there is a positive correlation between the generated current and the temperature of the electronic component, it is possible to determine whether the temperature rise is due to a loss due to abnormality or an increase in the generated current by monitoring the current flowing through the backflow prevention diodes D1 and D2. Can be corrected.

  Furthermore, the present invention preferably includes an external output means for outputting the result of the abnormality determination means.

  It is preferable to perform a predetermined external output according to the result of the abnormality determination means.

  As a result, not only the damaged portion can be detected, but also the electronic component that is the factor can be specified, so that repeated recurrence can be reduced.

  In the present invention, it is preferable that the external output means is an alarm or a control signal to the electronic component.

  FIG. 3 shows the logic for determining whether or not the temperature rise of the temperature sensor arranged in each part in the current collecting circuit 3 is detected, and the electronic component that causes the abnormality based on the result of the presence or absence.

  The abnormality detection circuit 4 determines abnormality based on this logic, and performs control for circuit protection or alarm / notification to the user.

  In one embodiment of the present invention, an abnormality is detected by heat being transmitted through the wiring material. However, the thickness of the wiring, the length, the influence of the heat sink on the substrate, etc. It is sufficient to design under optimum conditions as needed.

  Examples according to one embodiment of the present invention will be described below.

Example 1
When the screw of the terminal N1 is loosened due to a construction mistake, the contact resistance between the crimp terminal at the tip of the output cable of the solar cell string 1 and the terminal N1 increases, and heat is generated.

  When the temperature of the electrode of the terminal N1 rises, the wiring material 4 is a conductor such as copper having a good thermal conductivity, so that the heat is conducted through the wiring material 4 toward the backflow prevention diode D1 and the surge absorber ZNR2. Since the electronic component itself is sufficiently cooled by the heat radiation performance, the temperatures of the temperature sensors LDN and LP1 on the opposite sides of the backflow prevention diode D1 and the surge absorber ZNR2 hardly increase.

  Therefore, if only the temperature rise of the temperature sensor LN1 is detected, it can be determined that an abnormality has occurred at the terminal N1.

  This corresponds to No. 1 in FIG. 3, and the abnormality determination means 3b performs control (circuit protection operation or alarm / notification) predetermined as an abnormality occurring at the terminal N1.

(Example 2)
Surge absorbers protect circuits against high-voltage external noise such as lightning surges. However, when high voltages or currents exceeding the rated current flow, the internal electronic components deteriorate and are damaged. The power generation current of the battery string 2 leaks and heat is generated.

  Therefore, if a temperature increase is detected by the temperature sensors LP1 and LN1, it can be determined that an abnormality has occurred in the surge absorbers ZNR1 and ZNR2.

  This corresponds to No. 2 in FIG. 3, and the abnormality determination means 3b performs control (circuit protection operation or alarm / notification) predetermined as an abnormality has occurred in the surge absorbers ZNR1 and ZNR2.

(Example 3)
The determination by the abnormality determination means 3b is an example in which the temperature is corrected by the generated current.

  For example, as described above, since it is determined whether the temperature rise of the backflow prevention diode D1 is in the normal range or the abnormal value in consideration of the heat generated by the generated current, the temperature rise is detected by the temperature sensors LN1 and LDN. If there is, it can be determined that an abnormality has occurred in the backflow prevention diode D1.

  This corresponds to No. 3 in FIG. 3, and the abnormality determination means 3b performs control (circuit protection operation or alarm / notification) predetermined as an abnormality occurring in the backflow prevention diode D1.

  On the other hand, if the temperature sensor LP1 has an increase in temperature in addition to the temperature sensors LN1 and LDN described above, the backflow prevention diode D1 is abnormal as in No. 3, but the cause is different. Therefore, it can be determined that the overvoltage breakdown is caused by reverse connection of the positive electrode and the negative electrode of the solar cell string 2.

  This corresponds to No. 3 in FIG. 3, and the abnormality determination means 3b performs control (circuit protection operation or alarm / notification) predetermined as an abnormality occurring in the backflow prevention diode D1.

(Other examples)
In addition to Examples 1 to 3 described above, it is possible to detect an abnormality of an electronic component whose temperature has increased as shown in FIG.

  Further, for example, the current flowing through the temperature sensors LN1 and LN2 and the temperature rise are compared, the deterioration degree of the backflow prevention diodes D1 and D2 is compared, life prediction is performed, and a function of providing information to the user may be provided. This is possible and can be applied to other electronic components.

  As described above, according to the abnormality determination unit of the photovoltaic power generation apparatus of the present invention, the abnormal state of each electronic component can be detected with only a small number of temperature detection units.

1: Solar power generation device 2, 2a, 2b: Solar cell string 3: Current collecting circuit 3a: Temperature detection means 3b: Abnormality determination means 4: Wiring material 4a: Junction part 5: Power conditioners D1, D2: Backflow prevention diode P1, P2: Terminal (+ side) N1, N2: Terminal (-side)
PVO, NVO: Terminal block ZNR1-4: Input side surge absorber ZNR5, 6: Output side surge absorber LP1, LP2, LN1, LN2, LPO, LDN: Signal sending part of temperature sensor

Claims (4)

A plurality of solar cell strings and a current collecting circuit for collecting electric power from the plurality of solar cell strings,
A current collector comprising: a wiring material; an electronic component connected by the wiring material; and a plurality of temperature detecting means disposed at each of a plurality of junctions where the wiring material merges and adjacent to the electronic component Circuit,
A solar power generation apparatus comprising: an abnormality determination unit that determines an electronic component that is an abnormality factor based on a result of the temperature detection unit. 2. The photovoltaic power generation apparatus according to claim 1, wherein the abnormality determination unit determines a correction value obtained by subtracting a temperature generated by power from the solar cell string from a measurement value of the temperature detection unit. The solar power generation apparatus according to claim 1, further comprising an external output unit configured to output a result of the abnormality determination unit. The solar power generation apparatus according to claim 3, wherein the external output means is an alarm or a control signal to the electronic component.

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