JP2015049216A - Insulation resistance measurement device, insulation resistance measurement method and insulation monitor device - Google Patents

Insulation resistance measurement device, insulation resistance measurement method and insulation monitor device Download PDF

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JP2015049216A
JP2015049216A JP2013182995A JP2013182995A JP2015049216A JP 2015049216 A JP2015049216 A JP 2015049216A JP 2013182995 A JP2013182995 A JP 2013182995A JP 2013182995 A JP2013182995 A JP 2013182995A JP 2015049216 A JP2015049216 A JP 2015049216A
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resistance
power generation
generation unit
negative electrode
positive electrode
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政宣 吉富
Masanori Yoshitomi
政宣 吉富
隆文 石井
Takafumi Ishii
隆文 石井
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Eneos Corp
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JX Nippon Oil and Energy Corp
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Priority to PCT/JP2014/064329 priority patent/WO2015033627A1/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
    • G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
    • G01R27/16—Measuring impedance of element or network through which a current is passing from another source, e.g. cable, power line
    • G01R27/18—Measuring resistance to earth, i.e. line to ground
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
    • H02S50/00—Monitoring or testing of PV systems, e.g. load balancing or fault identification
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
    • G01R31/52—Testing for short-circuits, leakage current or ground faults
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy

Abstract

PROBLEM TO BE SOLVED: To provide an insulation resistance measurement device, an insulation resistance measurement method, and an insulation monitor device that can grasp reduction in insulation resistance without over-evaluating the insulation resistance and missing the reduction therein.SOLUTION: An insulation resistance measurement device 100 measures insulation resistance in a power generation part 11 made up of a solar battery string 18 plurally having a solar battery module 17. In the insulation resistance measurement device 100, in a state where a positive pole of the power generation part 11 is connected to a ground G, a voltage value in first load resistance between the positive pole thereof and the ground is measured, and further, in a state where a negative pole of the power generation part 11 is connected to the ground G, a voltage value in second load resistance between the negative pole thereof and the ground is measured. Furthermore, in a state where the positive pole of the power generation part 11 and the negative pole thereof are connected to each other, a voltage value in third load resistance between the positive pole and the negative pole is measured, where the first, second and third load resistance have resistance 12a commonly used, and are mutually set at the same predetermined resistance value.

Description

本発明は、絶縁抵抗測定装置、絶縁抵抗測定方法、及び絶縁監視装置に関する。   The present invention relates to an insulation resistance measuring device, an insulation resistance measuring method, and an insulation monitoring device.

太陽光発電システムでは、例えば太陽電池を含む太陽電池モジュールを複数有する太陽電池ストリング、又は、この太陽電池ストリングを複数有する太陽電池アレイにより発電部が構成され、この発電部によって太陽光が利用されて発電が行われる。このような発電部において絶縁不良があると、例えば人や物が絶縁不良箇所に触れたときや、絶縁不良箇所と金属架台等とが接触したとき、電気回路が外部と意図しない形で接触する地絡が生じる場合がある。そこで、当該地絡に係る絶縁抵抗を測定するものとして、例えば特許文献１に記載された絶縁抵抗測定装置が知られている。   In the solar power generation system, for example, a power generation unit is configured by a solar cell string including a plurality of solar cell modules including solar cells or a solar cell array including a plurality of solar cell strings, and sunlight is used by the power generation unit. Power generation is performed. If there is an insulation failure in such a power generation section, for example, when a person or object touches the insulation failure location, or when the insulation failure location and a metal mount contact, the electrical circuit contacts the outside in an unintended manner. A ground fault may occur. Therefore, for example, an insulation resistance measuring device described in Patent Document 1 is known as a device for measuring the insulation resistance related to the ground fault.

特許文献１に記載された絶縁抵抗測定装置では、発電部（太陽電池モジュール回路）の正極を接地させてなる接地線上の抵抗（既知抵抗）の電圧値、発電部の負極を接地させてなる接地線上の抵抗の電圧値、及び、発電部の極間の電圧値（直流母線電圧）を測定し、そして、これら測定結果に基づき絶縁抵抗を判定することが図られている。   In the insulation resistance measuring device described in Patent Document 1, the voltage value of the resistance (known resistance) on the ground line formed by grounding the positive electrode of the power generation unit (solar cell module circuit), and the grounding formed by grounding the negative electrode of the power generation unit It is intended to measure the voltage value of the resistance on the line and the voltage value (DC bus voltage) between the poles of the power generation unit, and determine the insulation resistance based on these measurement results.

特開平７−１７７６４６号公報JP-A-7-177646

ここで、上述の絶縁抵抗測定装置では、例えば次式（ａ１）に示すように、絶縁抵抗ＲＬについて、発電部における地絡点から正極までの電圧値Ｖ１と、発電部における地絡点から負極までの電圧値Ｖ２と、発電部の正極を接地させてなる接地線を流れる電流値Ｉ１と、発電部の負極を接地させてなる接地線を流れる電流値Ｉ２と、既知抵抗値ＲＤと、を用いて算出される場合がある。
ＲＬ＝（Ｖ１＋Ｖ２）／（Ｉ１＋Ｉ２）−ＲＤ …（ａ１） Here, in the above-described insulation resistance measuring apparatus, for example, as shown in the following equation (a1), for the insulation resistance RL , the voltage value V 1 from the ground fault point to the positive electrode in the power generation unit and the ground fault point in the power generation unit A voltage value V 2 from the negative electrode to the negative electrode, a current value I 1 that flows through a ground line formed by grounding the positive electrode of the power generation unit, a current value I 2 that flows through a ground line formed by grounding the negative electrode of the power generation unit, and a known resistance And may be calculated using the value RD .
R L = (V 1 + V 2 ) / (I 1 + I 2 ) −R D (a1)

このとき、電圧値（Ｖ１＋Ｖ２）としては、発電部の極間の開放電圧が用いられるのが一般的である。しかし、次式（ｂ１）に示すように、開放電発ＶＯＣは電圧値（Ｖ１＋Ｖ２）以上であることから、このことに起因して絶縁抵抗ＲＬを過大評価してしまい、絶縁抵抗ＲＬの低下を見逃す虞がある。特に、かかる虞は、発電部の劣化等のために当該発電部の直列抵抗が増大していると、電圧値（Ｖ１＋Ｖ２）が開放電圧ＶＯＣよりも著しく低下する場合があるために好ましくない。
（Ｖ１＋Ｖ２） ≦ ＶＯＣ …（ｂ１） At this time, as the voltage value (V 1 + V 2 ), an open circuit voltage between the electrodes of the power generation unit is generally used. However, as shown in the following equation (b1), since the open discharge generation V OC is equal to or higher than the voltage value (V 1 + V 2 ), the insulation resistance RL is overestimated due to this, and the insulation There is a risk that a drop in resistance RL may be overlooked. In particular, this is because the voltage value (V 1 + V 2 ) may be significantly lower than the open circuit voltage V OC when the series resistance of the power generation unit is increased due to deterioration of the power generation unit or the like. It is not preferable.
(V 1 + V 2 ) ≦ V OC (b1)

本発明は、上記実情に鑑みてなされたものであり、絶縁抵抗を過大評価せずにその低下を見逃すことなく把握可能な絶縁抵抗測定装置、絶縁抵抗測定方法及び絶縁監視装置を提供することを課題とする。   The present invention has been made in view of the above circumstances, and provides an insulation resistance measuring device, an insulation resistance measuring method, and an insulation monitoring device that can be grasped without overestimating the insulation resistance without overlooking the decrease. Let it be an issue.

上記課題を解決するため、本発明に係る絶縁抵抗測定装置は、少なくとも一つの太陽電池モジュールにより構成された発電部における絶縁抵抗を測定するための絶縁抵抗測定装置であって、発電部の正極を大地に接続させた状態で、該正極及び大地間の第１負荷抵抗における電圧値又は電流値を測定する第１測定部と、発電部の負極を大地に接地させた状態で、該負極及び大地間の第２負荷抵抗における電圧値又は電流値を測定する第２測定部と、発電部の正極及び負極を互いに接続させた状態で、該正極及び該負極間の第３負荷抵抗における電圧値又は電流値を測定する第３測定部と、を備えた測定部を具備し、第３負荷抵抗の抵抗値は、第１及び第２負荷抵抗が同じ抵抗値を有する場合、当該抵抗値以下とされ、第１及び第２負荷抵抗が互いに異なる抵抗値を有する場合、第１及び第２負荷抵抗の各抵抗値のうち小さい一方の抵抗値以下とされていること、を特徴とする。   In order to solve the above-mentioned problem, an insulation resistance measuring device according to the present invention is an insulation resistance measuring device for measuring an insulation resistance in a power generation unit constituted by at least one solar cell module, and includes a positive electrode of the power generation unit. A first measurement unit for measuring a voltage value or a current value at a first load resistance between the positive electrode and the ground in a state where the negative electrode and the ground are connected to the ground, and a negative electrode of the power generation unit is grounded to the ground. A voltage value at the third load resistance between the positive electrode and the negative electrode in a state where the second measurement unit for measuring the voltage value or the current value at the second load resistance between and the positive electrode and the negative electrode of the power generation unit are connected to each other A third measurement unit that measures a current value, and the resistance value of the third load resistor is equal to or less than the resistance value when the first and second load resistors have the same resistance value. , The first and second load resistances are Have different resistance values to have, that is less than one resistance smaller of the first and the resistance of the second load resistor, and wherein.

この地絡検出測定装置では、発電部の極間の負荷抵抗である第３負荷抵抗が、第１及び第２負荷抵抗が同じ抵抗値を有する場合にはその抵抗値以下とされ、第１及び第２負荷抵抗が互いに異なる抵抗値を有する場合には第１及び第２負荷抵抗の各抵抗値のうち小さい一方の抵抗値以下とされていることから、第３測定部で測定した極間電圧値である電圧値Ｖａについて次式（ｃ１）が成立する。よって、例えば当該電圧値Ｖａを上式（ａ１）の電圧値（Ｖ１＋Ｖ２）として用いることにより、絶縁抵抗を過大評価するおそれなく監視することが可能となり、その結果、絶縁抵抗の低下を見逃すことなく把握することが可能となる。
Ｖａ ≦ Ｖ３ ≦ （Ｖ１＋Ｖ２） …（ｃ１）
Ｖ３：第３負荷抵抗が絶縁抵抗及び所定抵抗値のときにおける極間電圧値。 In this ground fault detection and measurement device, when the first and second load resistors have the same resistance value, the third load resistance that is the load resistance between the poles of the power generation unit is set to be equal to or less than the resistance value. When the second load resistance has a different resistance value, the resistance value is less than one of the resistance values of the first and second load resistances. following formula (c1) is established for the voltage value V a is a value. Therefore, for example, by using the voltage value V a as the voltage value (V 1 + V 2 ) of the above formula (a1), it becomes possible to monitor without fear of overestimating the insulation resistance, and as a result, the insulation resistance is reduced. It becomes possible to grasp without missing.
V a ≦ V 3 ≦ (V 1 + V 2 ) ... (c1)
V 3 : Inter-electrode voltage value when the third load resistance is an insulation resistance and a predetermined resistance value.

また、上記作用効果を好適に奏する構成として、具体的には、下式（１−１）に基づいて絶縁抵抗を演算する演算部を備えたこと、が好ましい。
ＲＬ≧（ＲＤ３×Ｉａ−ＲＤ２×Ｉ２−ＲＤ１×Ｉ１）／（Ｉ１＋Ｉ２）…（１−１）
但し、Ｉ１：発電部の正極を大地に接続させた状態での第１負荷抵抗における電流値、Ｉ２：発電部の負極を大地に接続させた状態での第２負荷抵抗における電流値、Ｉａ：発電部の正極及び負極を互いに接続させた状態での第３負荷抵抗における電流値、ＲＤ１：前記第１負荷抵抗、ＲＤ２：前記第２負荷抵抗、ＲＤ３：前記第３負荷抵抗、ＲＬ：絶縁抵抗。 Further, as a configuration that preferably exhibits the above-described effects, it is preferable that a calculation unit that calculates an insulation resistance based on the following equation (1-1) is provided.
R L ≧ (R D3 × I a −R D2 × I 2 −R D1 × I 1 ) / (I 1 + I 2 ) (1-1)
Where I 1 : current value in the first load resistance with the positive electrode of the power generation unit connected to the ground, I 2 : current value in the second load resistance with the negative electrode of the power generation unit connected to the ground, I a : current value in the third load resistor in a state where the positive electrode and the negative electrode of the power generation unit are connected to each other, R D1 : the first load resistor, R D2 : the second load resistor, R D3 : the third load Resistance, R L : Insulation resistance.

また、下式（１−２）に基づいて地絡点の位置を演算する演算部を備えたこと、が好ましい。この場合、地絡点の位置についても把握可能となる。
Ｖ１：Ｖ２＝Ｉ１×（ＲＤ３×Ｉａ＋Ｉ２×（ＲＤ１−ＲＤ２））：
Ｉ２×（ＲＤ３×Ｉａ＋Ｉ１×（ＲＤ２−ＲＤ１））…（１−２）
但し、Ｖ１：地絡点から発電部の正極までの電圧値、Ｖ２：地絡点から発電部の負極までの電圧値、Ｉ１：発電部の正極を大地に接続させた状態での第１負荷抵抗における電流値、Ｉ２：発電部の負極を大地に接続させた状態での第２負荷抵抗における電流値、ＲＤ１：第１負荷抵抗、ＲＤ２：第２負荷抵抗、ＲＤ３：第３負荷抵抗。 Moreover, it is preferable to provide the calculating part which calculates the position of a ground fault point based on the following Formula (1-2). In this case, it is possible to grasp the position of the ground fault point.
V 1 : V 2 = I 1 × (R D3 × I a + I 2 × (R D1 −R D2 )):
I 2 × (R D3 × I a + I 1 × (R D2 −R D1 )) (1-2)
However, V 1 : Voltage value from the ground fault point to the positive electrode of the power generation unit, V 2 : Voltage value from the ground fault point to the negative electrode of the power generation unit, I 1 : In a state where the positive electrode of the power generation unit is connected to the ground Current value in the first load resistance, I 2 : Current value in the second load resistance in a state where the negative electrode of the power generation unit is connected to the ground, R D1 : First load resistance, R D2 : Second load resistance, R D3 : Third load resistance.

また、上記作用効果を好適に奏する構成として、具体的には、第１、第２及び第３負荷抵抗は、互いに同じ所定抵抗値を有すること、が好ましい。   In addition, as a configuration that preferably exhibits the above-described effects, specifically, it is preferable that the first, second, and third load resistors have the same predetermined resistance value.

また、測定部は、正極及び負極を有し、該正極及び該負極間の抵抗の電圧値を測定する電圧計と、電圧計の正極を、発電部の正極と大地との間で切替可能に接続する第１切替接続部と、電圧計の負極を、発電部の負極と大地との間で切替可能に接続する第２切替接続部と、を含んで構成され、第１、第２及び第３負荷抵抗は、電圧計の正極及び負極間の抵抗により構成されており、第１測定部は、第１切替接続部によって電圧計の正極を発電部の正極に接続させつつ、第２切替接続部によって電圧計の負極を大地に接続させた状態で、抵抗における電圧値又は電流値を測定し、第２測定部は、第１切替接続部によって電圧計の正極を大地に接続させつつ、第２切替接続部によって電圧計の負極を発電部の負極に接続させた状態で、抵抗における電圧値又は電流値を測定し、第３測定部は、第１切替接続部によって電圧計の正極を発電部の正極に接続させつつ、第２切替接続部によって電圧計の負極を発電部の負極に接続させた状態で、抵抗における電圧値又は電流値を測定することが好ましい。この場合、一つの電圧計のみによって絶縁抵抗を測定することが可能となる。   The measurement unit has a positive electrode and a negative electrode, and the voltmeter for measuring the voltage value of the resistance between the positive electrode and the negative electrode and the positive electrode of the voltmeter can be switched between the positive electrode and the ground of the power generation unit. A first switching connection portion to be connected; and a second switching connection portion for connecting the negative electrode of the voltmeter between the negative electrode of the power generation unit and the ground in a switchable manner. 3 load resistance is comprised by the resistance between the positive electrode of a voltmeter, and a negative electrode, and the 1st measurement part connects 2nd switching connection, connecting the positive electrode of a voltmeter to the positive electrode of an electric power generation part by a 1st switching connection part. In the state where the negative electrode of the voltmeter is connected to the ground by the unit, the voltage value or current value in the resistor is measured, and the second measuring unit connects the positive electrode of the voltmeter to the ground by the first switching connection unit, 2 Connect the negative electrode of the voltmeter to the negative electrode of the power The third measurement unit measures the voltage value or the current value, and connects the positive electrode of the voltmeter to the positive electrode of the power generation unit through the first switching connection unit, and the negative electrode of the voltmeter through the second switching connection unit. It is preferable to measure a voltage value or a current value in the resistor in a state where the resistor is connected. In this case, it is possible to measure the insulation resistance with only one voltmeter.

また、本発明に係る絶縁抵抗測定方法は、上記絶縁抵抗測定装置を用いて発電部における絶縁抵抗を測定すること、特徴とする。この絶縁抵抗測定方法においても、絶縁抵抗を過大評価せずにその低下を見逃すことなく把握することが可能となるという上記効果が奏される。また、本発明に係る絶縁監視装置は、上記絶縁抵抗測定装置を用いて発電部における絶縁抵抗を測定し、測定した絶縁抵抗が所定値を下回っている場合に、警報を発することを特徴とする。この絶縁監視装置においても、絶縁抵抗を過大評価せずにその低下を見逃すことなく把握することができると共に、当該絶縁抵抗の低下を警報により報知することができる。   Moreover, the insulation resistance measuring method according to the present invention is characterized in that the insulation resistance in the power generation unit is measured using the insulation resistance measuring device. This insulation resistance measuring method also has the above effect that it is possible to grasp the decrease without overestimating the insulation resistance without overestimating the insulation resistance. The insulation monitoring device according to the present invention is characterized in that the insulation resistance in the power generation unit is measured using the insulation resistance measurement device, and an alarm is issued when the measured insulation resistance is below a predetermined value. . Even in this insulation monitoring device, it is possible to grasp the decrease of the insulation resistance without overestimating it and not to overlook the decrease, and to notify the decrease of the insulation resistance by an alarm.

本発明によれば、絶縁抵抗を過大評価せずにその低下を見逃すことなく把握することが可能となる。   According to the present invention, it is possible to grasp the insulation resistance without overestimating and overlooking the decrease.

第１実施形態に係る絶縁抵抗測定装置を示す構成図である。It is a block diagram which shows the insulation resistance measuring apparatus which concerns on 1st Embodiment. 図１の絶縁抵抗測定装置を用いた絶縁抵抗測定方法を説明するための図である。It is a figure for demonstrating the insulation resistance measuring method using the insulation resistance measuring apparatus of FIG. 図１の絶縁抵抗測定装置を説明するためのＩＶカーブを示すグラフである。It is a graph which shows IV curve for demonstrating the insulation resistance measuring apparatus of FIG. 図１の絶縁抵抗測定装置の変形例を示す構成図である。It is a block diagram which shows the modification of the insulation resistance measuring apparatus of FIG. 第２実施形態に係る絶縁抵抗測定装置を示す構成図である。It is a block diagram which shows the insulation resistance measuring apparatus which concerns on 2nd Embodiment. 第３実施形態に係る絶縁抵抗測定装置を示す構成図である。It is a block diagram which shows the insulation resistance measuring apparatus which concerns on 3rd Embodiment.

以下、図面を参照しながら、本発明の好適な実施形態について詳細に説明する。なお、以下の説明では、同一又は相当要素には同一符号を付し、重複する説明は省略する。   Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the same or equivalent elements will be denoted by the same reference numerals, and redundant description will be omitted.

［第１実施形態］
本発明の第１実施形態について説明する。図１は、第１実施形態に係る絶縁抵抗測定装置を示す構成図である。図１に示すように、本実施形態の絶縁抵抗測定装置１００は、太陽光発電システムにおいて発電部１１の絶縁抵抗を測定するためのであり、電圧計１２、第１切替接続部１３及び第２切替接続部１４を、測定部１０として備えている。また、この絶縁抵抗測定装置１００は、制御ユニット（制御部）１５及び演算ユニット（演算部）１６を備えている。 [First Embodiment]
A first embodiment of the present invention will be described. FIG. 1 is a configuration diagram showing an insulation resistance measuring apparatus according to the first embodiment. As shown in FIG. 1, the insulation resistance measuring apparatus 100 of this embodiment is for measuring the insulation resistance of the power generation part 11 in a solar power generation system, and is the voltmeter 12, the 1st switching connection part 13, and the 2nd switching. The connection unit 14 is provided as the measurement unit 10. The insulation resistance measuring apparatus 100 includes a control unit (control unit) 15 and a calculation unit (calculation unit) 16.

発電部１１は、太陽光を利用して発電を行うためのものであり、複数（図中では、６つ）の太陽電池モジュール１７が直列接続されてなる太陽電池ストリング１８により構成されている。太陽電池モジュール１７は、例えばパネル状に構成されており、互いに直列接続された複数の太陽電池ユニットを備えている。なお、発電部１１は、複数の太陽電池ストリング１８が並列接続されてなる太陽電池アレイにより構成されていてもよい。   The power generation unit 11 is for generating power using sunlight, and includes a solar cell string 18 in which a plurality (six in the figure) of solar cell modules 17 are connected in series. The solar cell module 17 is configured in a panel shape, for example, and includes a plurality of solar cell units connected in series with each other. The power generation unit 11 may be configured by a solar cell array in which a plurality of solar cell strings 18 are connected in parallel.

この発電部１１は、例えば、不図示のパワーコンディショナに接続され、当該パワーコンディショナへ直流出力を供給する。パワーコンディショナは、供給された直流出力を交流出力に変換し、後段の電力系統（例えば商用電力系統）へ供給するものであり、絶縁トランスを有するトランス絶縁型であってもよいし、トランスレス（非絶縁）型であってもよい。ただし、絶縁抵抗を測定している間、発電部１１は、交流系統から絶縁されていることが好ましい。例えば、発電部１１が交流系統から絶縁されていない場合、交流系統の接地を絶縁不良と見分けることが困難で、正確な絶縁測定を実施できないおそれがあるためである。従って、トランスレス型のパワーコンディショナを用いる場合には、スイッチ装置等により発電部１１とパワーコンディショナとの電気的接続を切り離してから絶縁抵抗測定を行うことが好ましい。   For example, the power generation unit 11 is connected to a power conditioner (not shown) and supplies a DC output to the power conditioner. The power conditioner converts a supplied DC output into an AC output and supplies it to a subsequent power system (for example, a commercial power system). The power conditioner may be a transformer insulation type having an insulation transformer or a transformer-less type. (Non-insulating) type may be used. However, it is preferable that the power generation unit 11 is insulated from the AC system while measuring the insulation resistance. For example, when the power generation unit 11 is not insulated from the AC system, it is difficult to distinguish the grounding of the AC system from an insulation failure, and accurate insulation measurement may not be performed. Therefore, when a transformerless power conditioner is used, it is preferable to measure the insulation resistance after disconnecting the electrical connection between the power generation unit 11 and the power conditioner with a switch device or the like.

電圧計１２は、正極及び負極を有し、これら正極及び負極間に設けられた抵抗１２ａの電圧値を測定する。この電圧計１２は、測定した電圧値を演算ユニット１６へ出力する。電圧計１２としては、種々のものを用いることができ、ここでは、単極型のものが用いられている。また、抵抗１２ａは、既知の所定抵抗値ＲＤを有している。なお、ここでは、抵抗１２ａを電圧計１２と区別して説明しているが、抵抗１２ａは電圧計１２の内部抵抗（受信抵抗）であってもよい。また、電圧計１２の受信抵抗をＲ１とし、電圧計１２と並列に接続する抵抗をＲ２とする場合には、抵抗１２ａは、並列合成抵抗（１／（１／Ｒ１）＋（１／Ｒ２））を表す。 The voltmeter 12 has a positive electrode and a negative electrode, and measures a voltage value of a resistor 12a provided between the positive electrode and the negative electrode. The voltmeter 12 outputs the measured voltage value to the arithmetic unit 16. As the voltmeter 12, various types can be used, and here, a unipolar type is used. The resistor 12a has a known predetermined resistance value RD . Here, the resistor 12a is described separately from the voltmeter 12, but the resistor 12a may be an internal resistance (reception resistor) of the voltmeter 12. Further, when the receiving resistance of the voltmeter 12 is R1 and the resistance connected in parallel with the voltmeter 12 is R2, the resistor 12a has a parallel combined resistance (1 / (1 / R1) + (1 / R2) ).

第１切替接続部１３は、電圧計１２の正極を、発電部１１の正極と大地Ｇとの間で切替可能に接続する。具体的には、第１切替接続部１３は、切替えスイッチ１９ａを介して電圧計１２の正極（抵抗１２ａの正極側）から発電部１１の正極に接続された正極配線１３ｘと、切替えスイッチ１９ｂを介して電圧計１２の正極から大地Ｇに接続された正極配線１３ｙと、を含んでいる。   The first switching connection unit 13 connects the positive electrode of the voltmeter 12 so as to be switchable between the positive electrode of the power generation unit 11 and the ground G. Specifically, the first changeover connection unit 13 includes a changeover switch 19b and a positive electrode wiring 13x connected to the positive electrode of the power generation unit 11 from the positive electrode of the voltmeter 12 (the positive side of the resistor 12a) via the changeover switch 19a. And a positive electrode wiring 13 y connected to the ground G from the positive electrode of the voltmeter 12.

第２切替接続部１４は、電圧計１２の負極を、発電部１１の負極と大地Ｇとの間で切替可能に接続する。具体的には、第２切替接続部１４は、切替えスイッチ１９ｃを介して電圧計１２の負極（抵抗１２ａの負極側）から発電部１１の負極に接続された負極配線１４ｘと、切替えスイッチ１９ｄを介して電圧計１２の負極から大地Ｇに接続された負極配線１４ｙと、を含んでいる。   The second switching connection unit 14 connects the negative electrode of the voltmeter 12 to be switchable between the negative electrode of the power generation unit 11 and the ground G. Specifically, the second changeover connection unit 14 includes a changeover switch 19d and a negative electrode line 14x connected to the negative electrode of the power generation unit 11 from the negative electrode of the voltmeter 12 (the negative electrode side of the resistor 12a) via the changeover switch 19c. And a negative electrode wiring 14 y connected to the ground G from the negative electrode of the voltmeter 12.

切替えスイッチ１９ａ〜１９ｄとしては、電流を遮断するものであれば如何なる構成のものも用いることができ、例えば、ＦＥＴ（Field Effect Transistor）やＩＧＢＴ（Insulated GateBipolar Transistor）等の半導体スイッチ、機械式リレー等の電磁開閉器を用いることができる（以下のスイッチについて同様）。   As the change-over switches 19a to 19d, any configuration can be used as long as it cuts off the current. For example, semiconductor switches such as FET (Field Effect Transistor) and IGBT (Insulated Gate Bipolar Transistor), mechanical relays, etc. Can be used (the same applies to the following switches).

制御ユニット１５は、第１及び第２切替接続部１３，１４における切替えを制御するものである。具体的には、この制御ユニット１５は、切替えスイッチ１９ａをＯＮ且つ切替えスイッチ１９ｂをＯＦＦにして電圧計１２の正極を発電部１１の正極に接続して、切替えスイッチ１９ｃをＯＦＦ且つ切替えスイッチ１９ｄをＯＮにして電圧計１２の負極を大地Ｇに接続させる。   The control unit 15 controls switching in the first and second switching connection units 13 and 14. Specifically, the control unit 15 turns on the changeover switch 19a and turns off the changeover switch 19b, connects the positive electrode of the voltmeter 12 to the positive electrode of the power generation unit 11, turns off the changeover switch 19c, and turns off the changeover switch 19d. Turn ON to connect the negative electrode of the voltmeter 12 to the ground G.

また、制御ユニット１５は、切替えスイッチ１９ａをＯＦＦ且つ切替えスイッチ１９ｂをＯＮにして電圧計１２の正極を大地Ｇに接続させたとき、切替えスイッチ１９ｃをＯＮ且つ切替えスイッチ１９ｄをＯＦＦにして電圧計１２の負極を発電部１１の負極に接続させる。さらにまた、制御ユニット１５は、切替えスイッチ１９ａをＯＮ且つ切替えスイッチ１９ｂをＯＦＦにして電圧計１２の正極を発電部１１の正極に接続して、切替えスイッチ１９ｃをＯＮ且つ切替えスイッチ１９ｄをＯＦＦにして電圧計１２の負極を発電部１１の負極に接続させる。   Further, the control unit 15 turns off the changeover switch 19c and turns off the changeover switch 19d when the changeover switch 19a is turned off and the changeover switch 19b is turned on to connect the positive electrode of the voltmeter 12 to the ground G. Are connected to the negative electrode of the power generation unit 11. Furthermore, the control unit 15 turns on the changeover switch 19a and turns off the changeover switch 19b, connects the positive electrode of the voltmeter 12 to the positive electrode of the power generation unit 11, turns on the changeover switch 19c and turns off the changeover switch 19d. The negative electrode of the voltmeter 12 is connected to the negative electrode of the power generation unit 11.

演算ユニット１６は、電圧計１２で測定した電圧値に基づいて、絶縁抵抗を演算し算出する。この演算ユニット１６は、専用のＥＣＵ[Electronic Control Unit]で構成されていてもよく、あるいは、パソコン等の汎用コンピュータにおけるアプリケーションとして構成されてもよい。演算ユニット１６による演算の詳細については、後述する。   The arithmetic unit 16 calculates and calculates the insulation resistance based on the voltage value measured by the voltmeter 12. The arithmetic unit 16 may be configured by a dedicated ECU [Electronic Control Unit], or may be configured as an application in a general-purpose computer such as a personal computer. Details of the calculation by the calculation unit 16 will be described later.

なお、このように構成された絶縁抵抗測定装置１００では、発電部１１の正極を大地Ｇに接続させた状態における発電部１１の正極と大地Ｇとの間の負荷抵抗（以下、「第１負荷抵抗」）と、発電部１１の負極を大地Ｇに接地させた状態における発電部１１の負極と大地Ｇとの間の負荷抵抗（以下、「第２負荷抵抗」）と、発電部１１の正極及び負極を互いに接続させた状態における発電部１１の正極と負極との間の負荷抵抗（以下、「第３負荷抵抗」）と、は、全て電圧計１２の正極及び負極間の抵抗１２ａにより構成され、互いに同じ所定抵抗値ＲＤとなる。 In the insulation resistance measuring apparatus 100 configured in this way, the load resistance (hereinafter referred to as “first load”) between the positive electrode of the power generation unit 11 and the ground G in a state where the positive electrode of the power generation unit 11 is connected to the ground G. Resistance ”), the load resistance between the negative electrode of the power generation unit 11 and the ground G in a state where the negative electrode of the power generation unit 11 is grounded to the ground G (hereinafter,“ second load resistance ”), and the positive electrode of the power generation unit 11 The load resistance between the positive electrode and the negative electrode of the power generation unit 11 in a state where the negative electrode and the negative electrode are connected to each other (hereinafter referred to as “third load resistance”) is configured by the resistor 12 a between the positive electrode and the negative electrode of the voltmeter 12. And have the same predetermined resistance value RD .

次に、上記絶縁抵抗測定装置１００による絶縁抵抗の測定について説明する。図２は、図１の絶縁抵抗測定装置を用いた絶縁抵抗測定方法を説明するための図である。ここでは、図２に示すように、ある太陽電池モジュール１７ｘ，１７ｙ間で地絡が発生し、太陽電池ストリング１８の絶縁抵抗が絶縁抵抗ＲＬまで低下した場合の地絡状態を例にして説明する。 Next, measurement of insulation resistance by the insulation resistance measuring apparatus 100 will be described. FIG. 2 is a diagram for explaining an insulation resistance measurement method using the insulation resistance measurement apparatus of FIG. Here, as shown in FIG. 2, a ground fault occurs when a ground fault occurs between certain solar cell modules 17 x and 17 y, and the insulation resistance of the solar cell string 18 decreases to the insulation resistance RL. To do.

絶縁抵抗測定装置１００を用いた絶縁抵抗測定方法では、発電部１１を開放した状態において、図２（ａ）に示すように、制御ユニット１５により、切替えスイッチ１９ａ，１９ｄをＯＮとすると共に切替えスイッチ１９ｂ，１９ｃをＯＦＦとし、電圧計１２の正極を発電部１１の正極に接続すると共に、電圧計１２の負極を大地Ｇに接続する。これにより、発電部１１の正極側を大地Ｇへ接地させる、すなわち、発電部１１の正極から、切替えスイッチ１９ａ、抵抗１２ａ、切替えスイッチ１９ｄ及び大地Ｇへこの順に接続されてなる接地線を形成する。この状態で、電圧計１２により、抵抗１２ａの電圧値を、第１負荷抵抗における電圧値である第１電圧値ＶＤ１として測定する。何れの箇所で地絡が発生していても、その箇所の電位は正極以下であるため、抵抗１２ａを流れる電流Ｉ１の向きは、図２（a）に示した通りとなり、正極負極が固定されたモノポーラの電圧計１２でこの第１電圧値ＶＤ１を測定することが可能である。 In the insulation resistance measuring method using the insulation resistance measuring apparatus 100, the changeover switches 19a and 19d are turned on and the changeover switch is turned on by the control unit 15 as shown in FIG. 19b and 19c are turned OFF, the positive electrode of the voltmeter 12 is connected to the positive electrode of the power generation unit 11, and the negative electrode of the voltmeter 12 is connected to the ground G. Thereby, the positive electrode side of the power generation unit 11 is grounded to the ground G, that is, a ground wire is formed which is connected in this order from the positive electrode of the power generation unit 11 to the changeover switch 19a, the resistor 12a, the changeover switch 19d, and the ground G. . In this state, the voltmeter 12 measures the voltage value of the resistor 12a as the first voltage value V D1 that is the voltage value at the first load resistor. Because both have the have ground fault occurs at a point, the potential of that portion is positive or less, the direction of the current I 1 flowing through the resistor 12a becomes a as shown in FIG. 2 (a), the positive electrode negative electrode fixed It is possible to measure the first voltage value V D1 with the monopolar voltmeter 12 made.

また、図２（ｂ）に示すように、発電部１１を開放した状態において、制御ユニット１５により、切替えスイッチ１９ｂ，１９ｃをＯＮとすると共に切替えスイッチ１９ａ，１９ｄをＯＦＦとし、電圧計１２の正極を大地Ｇに接続すると共に、電圧計１２の負極を発電部１１の負極に接続する。これにより、発電部１１の負極側を大地Ｇへ接地させる、すなわち、発電部１１の負極から、切替えスイッチ１９ｃ、抵抗１２ａ、切替えスイッチ１９ｂ及び大地Ｇへこの順に接続されてなる接地線を形成する。この状態で、電圧計１２により、抵抗１２ａの電圧値を、第２負荷抵抗における電圧値である第２電圧値ＶＤ２として測定する。何れの箇所で地絡が発生していても、その箇所の電位は負極以上であるため、抵抗１２ａ流れる電流Ｉ２の向きは、図２（ｂ）に示した通りとなり、正極負極が固定されたモノポーラの電圧計１２でこの第２電圧値ＶＤ２を測定することが可能である。 Further, as shown in FIG. 2B, in a state where the power generation unit 11 is opened, the control unit 15 turns on the changeover switches 19b and 19c and turns off the changeover switches 19a and 19d, thereby Is connected to the ground G, and the negative electrode of the voltmeter 12 is connected to the negative electrode of the power generation unit 11. Thereby, the negative electrode side of the power generation unit 11 is grounded to the ground G, that is, a ground line is formed which is connected in this order from the negative electrode of the power generation unit 11 to the changeover switch 19c, the resistor 12a, the changeover switch 19b, and the ground G. . In this state, the voltmeter 12 measures the voltage value of the resistor 12a as the second voltage value V D2 that is the voltage value at the second load resistor. Because both are of ground fault at the point has not occurred, the potential of the point is more negative, the direction of the resistor 12a through current I 2 becomes a as shown in FIG. 2 (b), the positive electrode negative electrode is fixed The second voltage value V D2 can be measured with a monopolar voltmeter 12.

さらにまた、図２（ｃ）に示すように、制御ユニット１５により、切替えスイッチ１９ａ，１９ｃをＯＮとすると共に切替えスイッチ１９ｂ，１９ｄをＯＦＦとし、電圧計１２の正極を発電部１１の正極に接続すると共に、電圧計１２の負極を発電部１１の負極に接続する。これにより、発電部１１の極間を互いに接続させる、すなわち、発電部１１の正極から、切替えスイッチ１９ａ、抵抗１２ａ、切替えスイッチ１９ｃ及び発電部１１の負極へこの順に接続されてなる閉回路を形成する。この状態で、電圧計１２により、抵抗１２ａの電圧値を、第３負荷抵抗における電圧値である第３電圧値Ｖａとして測定する。この場合にも、正極負極が固定されたモノポーラの電圧計１２でこの第３電圧値Ｖａを測定可能であることは言うまでもない。 Furthermore, as shown in FIG. 2 (c), the control unit 15 turns on the changeover switches 19 a and 19 c and turns off the changeover switches 19 b and 19 d to connect the positive electrode of the voltmeter 12 to the positive electrode of the power generation unit 11. In addition, the negative electrode of the voltmeter 12 is connected to the negative electrode of the power generation unit 11. Thereby, the poles of the power generation unit 11 are connected to each other, that is, a closed circuit is formed which is connected in this order from the positive electrode of the power generation unit 11 to the changeover switch 19a, the resistor 12a, the changeover switch 19c, and the negative electrode of the power generation unit 11. To do. In this state, the voltage value of the resistor 12a is measured by the voltmeter 12 as a third voltage value Va that is a voltage value at the third load resistor. In this case, it is needless to say that can measure the third voltage value V a voltmeter 12 monopolar the positive electrode negative electrode is fixed.

このように発電部１１の正極を電圧計１２に接続するときには、必ず電圧計１２の正極に接続し、発電部１１の負極を電圧計１２に接続するときには、必ず電圧計１２の負極に接続する構成であるため、モノポーラの電圧計１２を利用することができる。なぜならば、発電部１１中のどの位置で地絡が発生しても、その電位は、太陽電池正極の電位以下であることから、発電部１１の正極を電圧計１２に接続した場合の抵抗１２ａ中の電流の向きは、発電部１１から大地Ｇに流れ込む向きとなり、また、発電部１１中のどの位置で地絡が発生しても、その電位は、太陽電池負極の電位以上であることから、発電部１１の負極を電圧計１２に接続した場合の抵抗１２ａ中の電流の向きは、大地Ｇから発電部１１に流れ込む向きとなるためである。   As described above, when the positive electrode of the power generation unit 11 is connected to the voltmeter 12, it is always connected to the positive electrode of the voltmeter 12, and when the negative electrode of the power generation unit 11 is connected to the voltmeter 12, it is always connected to the negative electrode of the voltmeter 12. Due to the configuration, a monopolar voltmeter 12 can be used. This is because even if a ground fault occurs at any position in the power generation unit 11, the potential is equal to or lower than the potential of the positive electrode of the solar cell, and thus the resistance 12 a when the positive electrode of the power generation unit 11 is connected to the voltmeter 12. The direction of the current inside is the direction of flowing from the power generation unit 11 to the ground G, and any potential in the power generation unit 11 is caused by the potential being equal to or higher than the potential of the solar cell negative electrode. This is because the direction of the current in the resistor 12 a when the negative electrode of the power generation unit 11 is connected to the voltmeter 12 is the direction of flowing from the ground G into the power generation unit 11.

続いて、演算ユニット１６により、第１〜第３電圧値ＶＤ１，ＶＤ２，Ｖａに基づき絶縁抵抗ＲＬを測定する。まず、絶縁抵抗ＲＬの測定の原理について、説明する。 Subsequently, the arithmetic unit 16 measures the insulation resistance RL based on the first to third voltage values V D1 , V D2 , and V a . First, the principle of measurement of the insulation resistance RL will be described.

発電部１１の正極側を大地Ｇへ接地させた状態（図２（ａ）参照）では、流れる電流値Ｉ１は、下式（２）で表せる。また、発電部１１の負極側を大地Ｇへ接地させた状態（図２（ｂ）参照）では、流れる電流値Ｉ２は、下式（３）で表せる。
Ｉ１＝Ｖ１／（ＲＬ＋ＲＤ） …（２）
Ｉ２＝Ｖ２／（ＲＬ＋ＲＤ） …（３）
Ｖ１：地絡点から発電部１１の正極までの太陽電池モジュール１７による電圧値、
Ｖ２：地絡点から発電部１１の負極までの太陽電池モジュール１７による電圧値、
ＲＤ：所定抵抗値。 In a state where the positive electrode side was grounded to the earth G of the power generation unit 11 (see FIG. 2 (a)), the current value I 1 which flows can be expressed by the following equation (2). Further, in a state where the negative electrode side of the power generation unit 11 is grounded to the ground G (see FIG. 2B), the flowing current value I 2 can be expressed by the following equation (3).
I 1 = V 1 / (R L + R D ) (2)
I 2 = V 2 / (R L + R D ) (3)
V 1 : voltage value by the solar cell module 17 from the ground fault point to the positive electrode of the power generation unit 11,
V 2 : voltage value by the solar cell module 17 from the ground fault point to the negative electrode of the power generation unit 11,
R D : predetermined resistance value.

従って、下式（４）〜（６）に示すように、電圧値（Ｖ１＋Ｖ２）及び電流値（Ｉ１＋Ｉ２）より、絶縁抵抗ＲＬを算出することができる。
Ｉ１＋Ｉ２＝（Ｖ１＋Ｖ２）／（ＲＬ＋ＲＤ） …（４）
（Ｖ１＋Ｖ２）／（Ｉ１＋Ｉ２）＝ＲＬ＋ＲＤ …（５）
ＲＬ＝（Ｖ１＋Ｖ２）／（Ｉ１＋Ｉ２）−ＲＤ …（６）
また、地絡点の位置を、次式に基づき判定することが可能である。
Ｖ１：Ｖ2＝Ｉ１：Ｉ2 Therefore, as shown in the following formulas (4) to (6), the insulation resistance RL can be calculated from the voltage value (V 1 + V 2 ) and the current value (I 1 + I 2 ).
I 1 + I 2 = (V 1 + V 2 ) / (R L + R D ) (4)
(V 1 + V 2 ) / (I 1 + I 2 ) = R L + R D (5)
R L = (V 1 + V 2 ) / (I 1 + I 2 ) −R D (6)
Further, the position of the ground fault point can be determined based on the following equation.
V 1 : V 2 = I 1 : I 2

図３は、図１の絶縁抵抗測定装置を説明するためのＩＶカーブを示すグラフである。図３において、ＩＶカーブＣ１は地絡点から発電部１１の正極までの太陽電池モジュール１７の４直列ＩＶカーブを示し、ＩＶカーブＣ２は地絡点から発電部１１の負極までの太陽電池モジュール１７の２直列ＩＶカーブを示し、ＩＶカーブＣ３は発電部１１の極間における太陽電池モジュール１７の６直列ＩＶカーブを示している。同じ電流値では、ＩＶカーブＣ３の電圧値は、ＩＶカーブＣ１の電圧値とＩＣカーブＣ２の電圧値との合計となっている。なお、図中では、説明のための便宜上、低電流部分を拡大・強調して示している。   FIG. 3 is a graph showing an IV curve for explaining the insulation resistance measuring apparatus of FIG. In FIG. 3, an IV curve C <b> 1 indicates a four series IV curve of the solar cell module 17 from the ground fault point to the positive electrode of the power generation unit 11, and an IV curve C <b> 2 indicates a solar cell module 17 from the ground fault point to the negative electrode of the power generation unit 11. The IV curve C3 shows the 6 series IV curve of the solar cell module 17 between the poles of the power generation unit 11. At the same current value, the voltage value of the IV curve C3 is the sum of the voltage value of the IV curve C1 and the voltage value of the IC curve C2. In the drawing, for the convenience of explanation, the low current portion is shown enlarged and emphasized.

発電部１１の正極側を大地Ｇへ接地させた状態、及び、発電部１１の負極側を大地Ｇへ接地させた状態では、負荷抵抗として、絶縁抵抗ＲＬと所定抵抗値ＲＤとが直列に接続されている。よって、図３に示すように、これらの状態の発電部１１の動作電圧である電圧値Ｖ１，Ｖ２は、ＩＶカーブＣ１，Ｃ２と直線Ｉ＝Ｖ（ＲＬ＋ＲＤ）との交点における電圧値である。発電部１１全体の開放電圧ＶＯＣは、ＶＯＣ＝ＶＯＣ１＋ＶＯＣ２であるため、Ｖ１＋Ｖ２≦ＶＯＣとなる。
ＶＯＣ１：地絡点から発電部１１の正極までの太陽電池モジュール１７の開放電圧、
ＶＯＣ２：地絡点から発電部１１の負極までの太陽電池モジュール１７の開放電圧。 In a state where the positive electrode side of the power generation unit 11 is grounded to the ground G and a state where the negative electrode side of the power generation unit 11 is grounded to the ground G, an insulation resistance R L and a predetermined resistance value R D are connected in series as a load resistance. It is connected to the. Therefore, as shown in FIG. 3, the voltage values V 1 and V 2 that are the operating voltages of the power generation unit 11 in these states are at the intersections of the IV curves C1 and C2 and the straight line I = V (R L + R D ). It is a voltage value. Since the open circuit voltage V OC of the entire power generation unit 11 is V OC = V OC1 + V OC2 , V 1 + V 2 ≦ V OC is satisfied .
V OC1 : Open-circuit voltage of the solar cell module 17 from the ground fault point to the positive electrode of the power generation unit 11,
V OC2: open-circuit voltage of the solar cell module 17 from the ground絡点to the negative electrode of the power generation unit 11.

よって、上式（６）の電圧値（Ｖ１＋Ｖ２）の代用として開放電圧ＶＯＣを用いると、絶縁抵抗ＲＬを過大評価し、絶縁抵抗ＲＬを見落としてしまう場合がある。特に、発電部１１の直列抵抗が増大していると、電圧値（Ｖ１＋Ｖ２）が開放電圧ＶＯＣよりも著しく低下することがあるため、絶縁抵抗ＲＬの過大評価が顕著となる。また、発電部１１が劣化している場合は、絶縁抵抗の低下と同時に、直列抵抗も増大していることが懸念される。 Therefore, if the open circuit voltage V OC is used as a substitute for the voltage value (V 1 + V 2 ) in the above equation (6), the insulation resistance RL may be overestimated and the insulation resistance RL may be overlooked. In particular, when the series resistance of the power generation unit 11 is increased, the voltage value (V 1 + V 2 ) may be significantly lower than the open circuit voltage V OC , and thus overestimation of the insulation resistance RL becomes significant. Moreover, when the electric power generation part 11 has deteriorated, we are anxious about the serial resistance also increasing simultaneously with the fall of insulation resistance.

これに対し、負荷抵抗（ＲＬ＋ＲＤ）における発電部１１全体の極間電圧Ｖ３は、Ｖ３≦Ｖ１＋Ｖ２である。そのため、上式（６）の電圧値（Ｖ１＋Ｖ２）の代用として極間電圧Ｖ３を用いると、絶縁抵抗ＲＬを過大評価することは回避できるが、当該絶縁抵抗ＲＬは未知であるため、極間電圧Ｖ３を正確に求めることは困難である。 On the other hand, the inter-electrode voltage V 3 of the entire power generation unit 11 at the load resistance (R L + R D ) is V 3 ≦ V 1 + V 2 . Therefore, if the inter-electrode voltage V 3 is used as a substitute for the voltage value (V 1 + V 2 ) in the above equation (6), it is possible to avoid overestimating the insulation resistance RL , but the insulation resistance RL is unknown. there, it is difficult to determine the inter-electrode voltage V 3 accurately.

この点、極間電圧Ｖ３の最低値は、次のようにして予測することができる。すなわち、絶縁抵抗ＲＬが低下すれば、負荷抵抗（ＲＬ＋ＲＤ）については所定抵抗値ＲＤまで低下するため、極間電圧Ｖ３の最低値は、第３電圧値Ｖａ（負荷抵抗が所定抵抗値ＲＤのときにおける発電部１１全体の極間電圧Ｖ３）となる。従って、Ｖａ≦Ｖ３≦Ｖ１＋Ｖ２となることから、上式（６）における電圧値（Ｖ１＋Ｖ２）として、第３電圧値Ｖａを用いれば、絶縁抵抗ＲＬを過大評価のおそれを抑制して測定できることが見出される。 In this regard, the minimum value of the inter-electrode voltage V 3 may be predicted as follows. That is, if the insulation resistance R L decreases, the load resistance (R L + R D ) decreases to the predetermined resistance value R D, so the minimum value of the interelectrode voltage V 3 is the third voltage value V a (load resistance Is the inter-electrode voltage V 3 ) of the entire power generation section 11 when the predetermined resistance value RD . Therefore, since the V a ≦ V 3 ≦ V 1 + V 2, as the voltage value in the above formula (6) (V 1 + V 2), the use of the third voltage value V a, overestimating the insulation resistance R L It is found that measurement can be performed while suppressing the fear of

そこで、本実施形態の演算ユニット１６では、下式（７），（８）に基づいて絶縁抵抗ＲＬを演算して測定する。なお、前述のように、下式（７），（８）において、ＶＤ１は発電部１１の正極を大地Ｇに接続させた状態での第１負荷抵抗における電圧値（第１電圧値）、ＶＤ２は発電部１１の負極を大地Ｇに接続させた状態での第２負荷抵抗における電圧値（第２電圧値）、Ｖａは発電部１１の正極及び負極を互いに接続させた状態での第３負荷抵抗における電圧値（第３電圧値）、Ｉ１は発電部１１の正極を大地Ｇに接続させた状態での第１負荷抵抗における電流値、Ｉ２は発電部１１の負極を大地Ｇに接続させた状態での第２負荷抵抗における電流値、Ｉａは発電部１１の正極及び負極を互いに接続させた状態での第３負荷抵抗における電流値、ＲＤは所定抵抗値、ＲＬは絶縁抵抗である。
ＲＬ≧（Ｉａ／（Ｉ１＋Ｉ２）−１）×ＲＤ …（７）
Ｉａ＝Ｖａ／ＲＤ，Ｉ１＝ＶＤ１／ＲＤ、Ｉ２＝ＶＤ２／ＲＤ …（８） Therefore, the arithmetic unit 16 of this embodiment calculates and measures the insulation resistance RL based on the following equations (7) and (8). As described above, in the following formulas (7) and (8), V D1 is a voltage value (first voltage value) at the first load resistor in a state where the positive electrode of the power generation unit 11 is connected to the ground G, V D2 is the voltage value at the second load resistor in a state of being connected to the negative electrode of the power generation unit 11 to the ground G (second voltage value), V a is in a state of being connected together to the positive and negative electrodes of the power generation portion 11 A voltage value (third voltage value) at the third load resistance, I 1 is a current value at the first load resistance in a state where the positive electrode of the power generation unit 11 is connected to the ground G, and I 2 is a ground value of the negative electrode of the power generation unit 11. The current value at the second load resistance in the state of being connected to G, I a is the current value of the third load resistance when the positive and negative electrodes of the power generation unit 11 are connected to each other, R D is the predetermined resistance value, R L is an insulation resistance.
R L ≧ (I a / (I 1 + I 2 ) −1) × R D (7)
I a = V a / R D , I 1 = V D1 / R D, I 2 = V D2 / R D ... (8)

上式（７）は、Ｖ１＋Ｖ２≧Ｖａ＝Ｉａ×ＲＤと上式（６）とにより得ることができる。すなわち、絶縁抵抗ＲＬを
（Ｉａ／（Ｉ１＋Ｉ２）−１）×ＲＤ
として評価すれば、絶縁抵抗ＲＬの真値は当該評価値以上であることから、絶縁抵抗ＲＬの低下を見逃すことなく把握することが可能となる。 The above equation (7) can be obtained from V 1 + V 2 ≧ V a = I a × RD and the above equation (6). That is, the insulation resistance RL is
(I a / (I 1 + I 2 ) −1) × R D
Since the true value of the insulation resistance RL is equal to or higher than the evaluation value, it is possible to grasp without missing the decrease in the insulation resistance RL .

なお、本実施形態では、図１に示すように、第１負荷抵抗と、第２負荷抵抗と、第３負荷抵抗とを、全て、電圧計１２の正極及び負極の間における抵抗１２ａにより構成する場合を説明した。このように、第１〜第３負荷抵抗を電圧計１２の測定対象となる抵抗のみにより構成する場合には、電流値を算出せずに、下式（９）に示すように電圧計１２によって測定された値を直接使用してよいことは言うまでもない。
ＲＬ≧（Ｖａ／（ＶＤ１＋ＶＤ２）−１）×ＲＤ …（９）
この場合、地絡点の位置についても電流値を使用せずに電圧計によって測定された値を直接使用してよいことも言うまでもない（次式参照）。
Ｖ１：Ｖ2＝ＶＤ１：ＶＤ２ In the present embodiment, as shown in FIG. 1, the first load resistor, the second load resistor, and the third load resistor are all configured by a resistor 12 a between the positive electrode and the negative electrode of the voltmeter 12. Explained the case. As described above, when the first to third load resistors are configured only by the resistance to be measured by the voltmeter 12, the voltmeter 12 does not calculate the current value, as shown in the following equation (9). Needless to say, the measured values may be used directly.
R L ≧ (V a / (V D1 + V D2 ) −1) × R D (9)
In this case, it goes without saying that the value measured by the voltmeter may be directly used for the position of the ground fault point without using the current value (see the following equation).
V 1 : V 2 = V D1 : V D2

ちなみに、所定抵抗値ＲＤは、絶縁抵抗ＲＬを精度よく測定するために、次の値とすることが好ましい。つまり、所定抵抗値ＲＤが小さすぎると地絡していることになることから、地絡と判断する閾値と同程度又は閾値よりも高いことが好ましい。所定抵抗値ＲＤが大きすぎると、電流値Ｉ１，Ｉ２の測定時に対地電位が安定するまで待つ時間が長くなって測定時間が長くなることから、短い測定時間での測定では、測定精度が低下する。所定抵抗値ＲＤは、測定に許容される時間を対地静電容量で除し、さらに所定値（ここでは、３）で除した値と同程度又はそれ以下であることが好ましい。 Incidentally, the predetermined resistance value RD is preferably set to the following value in order to accurately measure the insulation resistance RL . That is, if the predetermined resistance value RD is too small, a ground fault occurs. Therefore, it is preferable that the threshold value is equal to or higher than the threshold value for determining a ground fault. If the predetermined resistance value RD is too large, the time to wait until the ground potential stabilizes when measuring the current values I1 and I2 becomes longer and the measurement time becomes longer. Therefore, the measurement accuracy decreases in the measurement with a short measurement time. To do. The predetermined resistance value RD is preferably equal to or less than a value obtained by dividing the time allowed for measurement by the ground capacitance and further dividing by a predetermined value (here, 3).

以上、本実施形態では、発電部１１の正極を大地Ｇに接続させた状態で第１電圧値ＶＤ１が測定され、発電部１１の負極を大地Ｇに接地させた状態で第２電圧値ＶＤ２が測定され、発電部１１の正極及び負極を互いに接続させた状態で第３電圧値Ｖａが測定される。ここで、発電部１１の正極及び大地間の第１負荷抵抗と、発電部１１の負極及び大地間の第２負荷抵抗と、発電部１１の正極及び該負極間の第３負荷抵抗と、は、抵抗１２ａが兼用されて互いに同じ所定抵抗値ＲＤとされていることから、第３電圧値Ｖａについて、Ｖａ≦Ｖ３≦Ｖ１＋Ｖ２が成立する。 As described above, in the present embodiment, the first voltage value V D1 is measured with the positive electrode of the power generation unit 11 connected to the ground G, and the second voltage value V D with the negative electrode of the power generation unit 11 grounded to the ground G. D2 is measured, and the third voltage value Va is measured in a state where the positive electrode and the negative electrode of the power generation unit 11 are connected to each other. Here, the first load resistance between the positive electrode and the ground of the power generation unit 11, the second load resistance between the negative electrode and the ground of the power generation unit 11, and the third load resistance between the positive electrode of the power generation unit 11 and the negative electrode are: Since the resistor 12a is also used to have the same predetermined resistance value R D , V a ≦ V 3 ≦ V 1 + V 2 is established for the third voltage value V a .

よって、第３電圧値Ｖａを上式（６）の電圧値（Ｖ１＋Ｖ２）として用いた上式（７）の右辺でもって絶縁抵抗ＲＬを算出することで、絶縁抵抗ＲＬを過大評価するおそれなく監視でき、その結果、絶縁抵抗ＲＬの低下を見逃すことなく把握することが可能となる。加えて、例えば装置構成及び絶縁抵抗ＲＬの算出に係るソフトウェアが簡易なものとなり、動作が確実で安価な絶縁抵抗測定装置１００を製造することも可能となる。 Therefore, by calculating the insulation resistance RL with the right side of the above equation (7) using the third voltage value V a as the voltage value (V 1 + V 2 ) of the above equation (6), the insulation resistance RL is It is possible to monitor without fear of overestimation, and as a result, it becomes possible to grasp without missing a decrease in the insulation resistance RL . In addition, for example, the software relating to the calculation of the device configuration and the insulation resistance RL becomes simple, and it is possible to manufacture the insulation resistance measuring device 100 that is reliable and inexpensive in operation.

また、本実施形態においては、上述したように、地絡点の位置を演算して判定することができ、よって、地絡点の位置についても把握可能となる。   Further, in the present embodiment, as described above, the position of the ground fault point can be calculated and determined, so that the position of the ground fault point can also be grasped.

また、本実施形態では、上述したように、一つの電圧計１２のみによって絶縁抵抗ＲＬを測定することが可能となり、簡易な構成で絶縁抵抗ＲＬを測定することが可能となる。また、上述したように、電圧計１２としては、電圧の向きを判定可能な電圧計である双極型（バイポーラ）のもの等が要されず、単極型（モノポーラ）のものを用いることができる。すなわち、本実施形態によれば、正電圧だけ計れる電圧計１２を１台で、３つの測定（電圧値ＶＤ１，ＶＤ２，Ｖａの測定）を実現することができる。その結果、低コスト化するだけでなく、メンテナンスを容易化することが可能となる。 Further, in the present embodiment, as described above, it is possible only by a single voltmeter 12 to measure the insulation resistance R L, it is possible to measure the insulation resistance R L with a simple configuration. Further, as described above, the voltmeter 12 does not need a bipolar type (bipolar) that is a voltmeter capable of determining the direction of the voltage, and can be a unipolar type (monopolar). . That is, according to the present embodiment, it is possible to realize three measurements (measurement of voltage values V D1 , V D2 , and V a ) with one voltmeter 12 that can measure only a positive voltage. As a result, not only cost reduction but also maintenance can be facilitated.

上記において、第１及び第２切替接続部１３，１４と切替えスイッチ１９ａ，１９ｄと抵抗１２ａと電圧計１２とは、発電部１１の正極を大地Ｇに接続させて第１電圧値ＶＤ１を測定する第１測定部を構成する。また、第１及び第２切替接続部１３，１４と切替えスイッチ１９ｂ、１９ｃと抵抗１２ａと電圧計１２とは、発電部１１の負極を大地Ｇに接地させて第２電圧値ＶＤ２を測定する第２測定部を構成する。また、第１及び第２切替接続部１３，１４と切替えスイッチ１９ａ、１９ｃと抵抗１２ａと電圧計１２とは、発電部１１の正極及び負極を互いに接続させて第３電圧値Ｖａを測定する第３測定部を構成する。 In the above, the first and second changeover connection parts 13 and 14, the changeover switches 19a and 19d, the resistor 12a and the voltmeter 12 measure the first voltage value VD1 by connecting the positive electrode of the power generation part 11 to the ground G. The first measurement unit is configured. The switch 19b switched to the first and second switch connection 13, 14, and 19c and the resistor 12a and the voltmeter 12 measures a second voltage value V D2 grounds the negative electrode to the earth G of the power generation portion 11 A second measurement unit is configured. The switch 19a switching the first and second switch connection 13, 14, and 19c and the resistor 12a and the voltmeter 12 measures a third voltage value V a by mutually connecting the positive and negative electrodes of the power generation portion 11 A third measurement unit is configured.

図４は、図１の絶縁抵抗測定装置の変形例を示す構成図である。図４に示すように、絶縁抵抗測定装置１００は、切替えスイッチ１９ａ，１９ｂ（図１参照）に代えてＣ接点２０ａを備えていると共に、切替えスイッチ１９ｃ，１９ｄ（図１参照）に代えてＣ接点２０ｂを備えていてもよい。これにより、配線を簡易化することができ、ひいては、一層簡易な構成で絶縁抵抗ＲＬを測定することが可能となる。 FIG. 4 is a configuration diagram showing a modification of the insulation resistance measuring apparatus of FIG. As shown in FIG. 4, the insulation resistance measuring apparatus 100 includes a C contact 20a in place of the changeover switches 19a and 19b (see FIG. 1) and a C contact in place of the changeover switches 19c and 19d (see FIG. 1). A contact 20b may be provided. As a result, the wiring can be simplified, and as a result, the insulation resistance RL can be measured with a simpler configuration.

なお、本実施形態において、第１負荷抵抗、第２負荷抵抗及び第３負荷抵抗を電圧計１２に並列接続された抵抗１２ａだけで構成するのではなく、保護抵抗を含めて構成してもよい。すなわち、第１切替接続部１３及び／又は第２切替接続部１４に、第１〜第３負荷抵抗の各抵抗値が互いに等しくなるように、一つ又は複数の保護抵抗を配置してもよい。この場合、演算ユニット１６では、下式（１０），（１１）に基づいて絶縁抵抗ＲＬを演算して測定できる。なお、下式（１０），（１１）において、ＶＤ１は発電部１１の正極を大地Ｇに接続させた状態での抵抗１２ａにおける電圧値、ＶＤ２は発電部１１の負極を大地Ｇに接続させた状態での抵抗１２ａにおける電圧値、Ｖａは発電部１１の正極及び負極を互いに接続させた状態での抵抗１２ａにおける電圧値、Ｉ１は発電部１１の正極を大地Ｇに接続させた状態での第１負荷抵抗における電流値、Ｉ２は発電部１１の負極を大地Ｇに接続させた状態での第２負荷抵抗における電流値、ＲＤは抵抗１２ａの抵抗値、ＲＰは各第１〜第３負荷抵抗における保護抵抗値の和、ＲＬは絶縁抵抗値である。ここでは、所定抵抗値は（ＲＤ＋ＲＰ）である。
ＲＬ≧（Ｉａ／（Ｉ１＋Ｉ２）−１）×（ＲＤ＋ＲＰ） …（１０）
Ｉａ＝Ｖａ／ＲＤ、Ｉ１＝ＶＤ１／ＲＤ、Ｉ２＝ＶＤ２／ＲＤ …（１１） In the present embodiment, the first load resistor, the second load resistor, and the third load resistor are not configured by only the resistor 12a connected in parallel to the voltmeter 12, but may be configured including a protective resistor. . That is, one or a plurality of protective resistors may be arranged in the first switching connection portion 13 and / or the second switching connection portion 14 so that the resistance values of the first to third load resistors are equal to each other. . In this case, the calculation unit 16 can calculate and measure the insulation resistance RL based on the following equations (10) and (11). In the following formulas (10) and (11), V D1 is a voltage value in the resistor 12a in a state where the positive electrode of the power generation unit 11 is connected to the ground G, and V D2 is a negative value of the power generation unit 11 connected to the ground G. voltage value at the resistor 12a in a state of being, V a is the voltage value, I 1 is to connect the positive electrode of the power generation unit 11 to the ground G in the resistance 12a in the state of being connected together to the positive and negative electrodes of the power generation portion 11 The current value in the first load resistance in the state, I 2 is the current value in the second load resistance in a state where the negative electrode of the power generation unit 11 is connected to the ground G, RD is the resistance value of the resistor 12a, and RP is each The sum of the protective resistance values in the first to third load resistors, R L is the insulation resistance value. Here, the predetermined resistance value is (R D + R P ).
R L ≧ (I a / (I 1 + I 2 ) −1) × (R D + R P ) (10)
I a = V a / R D , I 1 = V D1 / R D, I 2 = V D2 / R D ... (11)

［第２実施形態］
次に、本発明の第２実施形態について説明する。本実施形態の説明では、上記第１実施形態と異なる点について主に説明する。 [Second Embodiment]
Next, a second embodiment of the present invention will be described. In the description of the present embodiment, differences from the first embodiment will be mainly described.

図５は、第２実施形態に係る絶縁抵抗測定装置を示す構成図である。図５に示すように、本実施形態の絶縁抵抗測定装置２００が上記第１実施形態と異なる点は、測定部１０（図１参照）に代えて、第１〜第３測定部２１１〜２１３を有する測定部２１０を備えている点である。   FIG. 5 is a configuration diagram showing an insulation resistance measuring apparatus according to the second embodiment. As shown in FIG. 5, the insulation resistance measuring apparatus 200 of the present embodiment is different from the first embodiment in that the first to third measuring units 211 to 213 are replaced with the measuring unit 10 (see FIG. 1). It is the point provided with the measurement part 210 which has.

第１測定部２１１は、所定抵抗値ＲＤを有する第１抵抗１２ａ１と、この第１抵抗１２ａ１の電圧値を測定する第１電圧計１２１と、切替えスイッチ２１９ａを介して第１電圧計１２１の正極（第１抵抗１２ａ１の正極側）を発電部１１の正極に接続する第１配線２１１と、切替えスイッチ２１９ｂを介して第１電圧計１２１の負極（第１抵抗１２ａ１の負極側）を大地Ｇに接続する第１配線２２１と、を含んでいる。 First measuring unit 211 includes a first resistor 12a1 having a predetermined resistance value R D, a first voltmeter 12 1 for measuring the voltage value of the first resistor 12a1, a first voltage via the changeover switch 219a total of 12 1 of the positive electrode positive first wiring 21 1 connected to the pole, switching first voltmeter 12 1 of the negative electrode via a switch 219b (the negative electrode side of the first resistor 12a1 of the power generation unit 11 (the positive electrode side of the first resistor 12a1) ) and the first wiring 22 1 connected to the ground G, contains.

第２測定部２１２は、所定抵抗値ＲＤを有する第２抵抗１２ａ２と、この第２抵抗１２ａ２の電圧値を測定する第２電圧計１２２と、切替えスイッチ２１９ｃを介して第２電圧計１２２の正極（第２抵抗１２ａ２の正極側）を大地Ｇに接続する第２配線２１２と、切替えスイッチ２１９ｄを介して第２電圧計１２２の負極（第２抵抗１２ａ２の負極側）を発電部１１の負極に接続する第２配線２２２と、を含んでいる。 The second measuring unit 212 includes a second resistor 12a2 having a predetermined resistance value R D, a second voltmeter 12 2 that measures a voltage value of the second resistor 12a2, the second voltage via the changeover switch 219c meter 12 generating a second positive electrode (positive electrode side of the second resistor 12a2) and the second wiring 21 2 connected to the ground G, through the changeover switch 219d second voltmeter 12 2 of the negative electrode (negative electrode side of the second resistor 12a2) the second wiring 22 2 connected to the negative electrode parts 11, contains.

第３測定部２１３は、所定抵抗値ＲＤを有する第３抵抗１２ａ３と、この第３抵抗１２ａ３の電圧値を測定する第３電圧計１２３と、切替えスイッチ２１９ｅを介して第３電圧計１２３の正極（第３抵抗１２ａ３の正極側）を発電部１１の正極に接続する第３配線２１３と、切替えスイッチ２１９ｆを介して第３電圧計１２３の負極（第３抵抗１２ａ３の負極側）を発電部１１の負極に接続する第３配線２２３と、を含んでいる。 Third measuring unit 213 includes a third resistor 12a3 having a predetermined resistance value R D, a third voltmeter 12 3 for measuring the voltage value of the third resistor 12a3, the third voltage through the changeover switch 219e meter 12 3 of the positive electrode (positive electrode side of the third resistor 12a3) and the third wiring 21 3 connected to the positive electrode of the power generation portion 11, via a changeover switch 219f third voltmeter 12 3 of the negative electrode (negative electrode side of the third resistor 12a3 ) and the third wiring 22 3 connected to the negative electrode of the power generation unit 11 includes a.

この本実施形態の絶縁抵抗測定装置２００を用いた絶縁抵抗測定方法では、制御ユニット１５により、切替えスイッチ２１９ａ，２１９ｂをＯＮとすると共に切替えスイッチ２１９ｃ〜２１９ｆをＯＦＦとし、発電部１１の正極側を大地Ｇへ接地させる。この状態で、第１電圧計１２１により、第１抵抗１２ａ１の電圧値を第１電圧値ＶＤ１として測定する。 In the insulation resistance measuring method using the insulation resistance measuring apparatus 200 of the present embodiment, the control unit 15 turns on the changeover switches 219a and 219b and turns off the changeover switches 219c to 219f so that the positive electrode side of the power generation unit 11 is turned on. Ground to ground G. In this state, the first voltmeter 12 1, measures the voltage value of the first resistor 12a1 as a first voltage value V D1.

また、制御ユニット１５により、切替えスイッチ２１９ｃ，２１９ｄをＯＮとすると共に切替えスイッチ２１９ａ，２１９ｂ，２１９ｅ，２１９ｆをＯＦＦとし、発電部１１の負極側を大地Ｇへ接地させる。この状態で、第２電圧計１２２により、第２抵抗１２ａ２の電圧値を第２電圧値ＶＤ２として測定する。 Further, the control unit 15 turns on the changeover switches 219c and 219d and turns off the changeover switches 219a, 219b, 219e, and 219f, and grounds the negative electrode side of the power generation unit 11 to the ground G. In this state, the second voltmeter 12 2, measures the voltage value of the second resistor 12a2 as the second voltage value V D2.

さらにまた、制御ユニット１５により、切替えスイッチ２１９ｅ，２１９ｆをＯＮとすると共に切替えスイッチ２１９ａ〜２１９ｄをＯＦＦとし、発電部１１の極間を互いに接続させる。この状態で、第３電圧計１２３により、第４抵抗１２ａ３の電圧値を第３電圧値Ｖａとして測定する。 Furthermore, the control unit 15 turns on the changeover switches 219e and 219f and turns off the changeover switches 219a to 219d to connect the poles of the power generation unit 11 to each other. In this state, the third voltmeter 12 3, measures the voltage value of the fourth resistor 12a3 as a third voltage value V a.

以上、本実施形態においても、第１負荷抵抗と第２負荷抵抗と第３負荷抵抗とが互いに同じ所定抵抗値ＲＤとなっており、よって、絶縁抵抗ＲＬを過大評価するおそれなく監視し、絶縁抵抗ＲＬの低下を見逃すことなく把握することが可能となるという上記作用効果が奏される。 As described above, also in the present embodiment, the first load resistance, the second load resistance, and the third load resistance have the same predetermined resistance value RD, and therefore, the insulation resistance RL can be monitored without overestimating. Thus, the above-described effect is achieved that it is possible to grasp the decrease in the insulation resistance RL without overlooking it.

なお、本実施形態において、第１抵抗１２ａ１と第２抵抗１２ａ２と第３抵抗１２ａ３とが全て等しい抵抗値ＲＤを有することとして説明したが、第１負荷抵抗と第２負荷抵抗と第３負荷抵抗とが互いに同じ所定抵抗値であればよく、電圧計１２１〜１２３の測定対象となる抵抗１２ａ１〜１２ａ３を全て同じ値にする必要はない。例えば、図５において、第１配線２１１に第１保護抵抗Ｒ１を、第２配線２２２に第２保護抵抗Ｒ２を、第３配線２１３に第３保護抵抗Ｒ３をそれぞれ配置し、第１負荷抵抗（第１保護抵抗Ｒ１と第１抵抗１２ａ１との和）と、第２負荷抵抗（第２保護抵抗Ｒ２と第２抵抗１２ａ２との和）と、第３負荷抵抗（第３保護抵抗Ｒ３と第３抵抗１２ａ３との和）が互いに同じ所定抵抗値になるように設計することができる。 In the present embodiment, the first resistor 12a1, the second resistor 12a2, and the third resistor 12a3 are all described as having the same resistance value RD . However, the first load resistor, the second load resistor, and the third load are described. The resistors need only have the same predetermined resistance value, and the resistors 12a1 to 12a3 to be measured by the voltmeters 12 1 to 12 3 need not all have the same value. For example, in FIG. 5, a first protection resistor R 1 to the first wiring 21 1, second protective resistor R 2, the third protection resistor R 3 respectively arranged in the third wiring 21 3 to the second wiring 22 2 a first load resistor (the sum of the first protective resistor R 1 and the first resistor 12a1), and a second load resistor (the sum of the second protective resistor R 2 and the second resistor 12a2), the third load resistor ( it can be a third protection resistor R 3 the sum of the third resistor 12a3) is designed to mutually the same predetermined resistance value.

さらにまた、本実施形態においては、第１、第２及び第３負荷抵抗は互いに同じ所定抵抗値を有しなくともよく、要は、第３負荷抵抗の抵抗値が、第１及び第２負荷抵抗が同じ抵抗値を有する場合には当該抵抗値以下とされ、第１及び第２負荷抵抗が互いに異なる抵抗値を有する場合には第１及び第２負荷抵抗の各抵抗値のうち小さい一方（大きくない一方）の抵抗値以下とされていてもよい。この場合、例えば以下に例示するように、絶縁抵抗ＲＬの低下を見逃すことなく把握することができ、地絡点の位置（地絡位置）を把握することができる。 Furthermore, in the present embodiment, the first, second and third load resistors do not have to have the same predetermined resistance value. In short, the resistance value of the third load resistor is the first and second loads. When the resistors have the same resistance value, the resistance value is equal to or less than the resistance value. When the first and second load resistors have different resistance values, the smaller one of the resistance values of the first and second load resistors ( It may be set to be equal to or less than the resistance value of one that is not large. In this case, for example, as illustrated below, it is possible to grasp without missing the decrease in the insulation resistance RL , and it is possible to grasp the position of the ground fault point (ground fault position).

まず、発電部１１の正極を、抵抗値ＲＤ１を有する第１負荷抵抗を介して接地した際に、この第１負荷抵抗に発生する電圧を第１電圧値ＶＤ１とし、このときの地絡点から当該正極までの発電部１１の電圧を電圧値Ｖ１とする。発電部１１の負極を、抵抗値ＲＤ２を有する第２負荷抵抗を介して接地した際に、この第２負荷抵抗に発生する電圧を第２電圧値ＶＤ２とし、このときの地絡点から負極までの発電部１１の電圧を電圧値Ｖ２とする。発電部１１の正極及び負極間を、抵抗値ＲＤ３を有する第３負荷抵抗を介して接続した際に、この第３負荷抵抗に発生する電圧を第３電圧値Ｖａとする。 First, when the positive electrode of the power generation unit 11 is grounded via the first load resistor having the resistance value R D1 , the voltage generated in the first load resistor is set to the first voltage value V D1, and the ground fault at this time the voltage of the power generation unit 11 to the positive electrode and the voltage value V 1 from the point. When the negative electrode of the power generation unit 11 is grounded via the second load resistor having the resistance value R D2 , the voltage generated in the second load resistor is set to the second voltage value V D2, and the ground fault point at this time the voltage of the power generation portion 11 to the negative electrode and the voltage value V 2. When the positive electrode and the negative electrode of the power generation unit 11 are connected via a third load resistor having a resistance value R D3 , a voltage generated in the third load resistor is defined as a third voltage value Va.

この場合、次式（Ａ），（Ｂ）が成立する。また、ＲＤ３≦ＲＤ１、且つ、ＲＤ３≦ＲＤ２より、次式（Ｃ）が成立する。
ＶＤ１＝Ｖ１×ＲＤ１／（ＲＬ＋ＲＤ１) …（Ａ）
ＶＤ２＝Ｖ２×ＲＤ２／（ＲＬ＋ＲＤ２) …（Ｂ）
Ｖ１＋Ｖ２≧Ｖａ …（Ｃ） In this case, the following expressions (A) and (B) are established. Further, from R D3 ≦ R D1 and R D3 ≦ R D2 , the following expression (C) is established.
V D1 = V 1 × R D1 / (R L + R D1 ) (A)
V D2 = V 2 × R D2 / (R L + R D2 ) (B)
V 1 + V 2 ≧ V a (C)

そして、上式（Ａ），（Ｂ），（Ｃ）より、下式を得ることができる。
ＲＬ≧ＲＤ１×ＲＤ２×（Ｖａ−ＶＤ１−ＶＤ２）
／（ＲＤ１×ＶＤ２＋ＲＤ２×ＶＤ１）
すなわち、Ｖ１＋Ｖ２＝Ｖａとみなし、絶縁抵抗ＲＬを
ＲＤ１×ＲＤ２×（Ｖａ−ＶＤ１−ＶＤ２）／（ＲＤ１×ＶＤ２＋ＲＤ２×ＶＤ１）
として評価すれば、絶縁抵抗ＲＬの真値は当該評価値以上であることから、絶縁抵抗ＲＬの低下を見逃すことなく把握することが可能となる。 Then, the following equation can be obtained from the above equations (A), (B), and (C).
R L ≧ R D1 × R D2 × (V a −V D1 −V D2 )
/ (R D1 × V D2 + R D2 × V D1 )
That is, it is assumed that V 1 + V 2 = V a, and the insulation resistance RL is R D1 × R D2 × (V a −V D1 −V D2 ) / (R D1 × V D2 + R D2 × V D1 )
Since the true value of the insulation resistance RL is equal to or higher than the evaluation value, it is possible to grasp without missing the decrease in the insulation resistance RL .

さらにこの場合、下式により地絡位置を推定することが可能である。
Ｖ１：Ｖ２＝ＶＤ１×（ＲＤ２×Ｖａ＋ＶＤ２×（ＲＤ１−ＲＤ２））：
ＶＤ２×（ＲＤ１×Ｖａ＋ＶＤ１×（ＲＤ２−ＲＤ１））
なお、負荷抵抗の抵抗値ＲＤ１，ＲＤ２，ＲＤ３の何れも、複数の抵抗の組み合わせで構成することができる。このとき、その一部の抵抗の電圧値から上記電圧値ＶＤ１，ＶＤ２，Ｖａを求めることで、上記計算を行ってもよい。 Furthermore, in this case, it is possible to estimate the ground fault position by the following equation.
V 1 : V 2 = V D1 × (R D2 × V a + V D2 × (R D1 −R D2 )):
V D2 × (R D1 × V a + V D1 × (R D2 −R D1 ))
Note that any of the resistance values R D1 , R D2 , and R D3 of the load resistance can be configured by a combination of a plurality of resistors. At this time, the above calculation may be performed by obtaining the voltage values V D1 , V D2 , and V a from the voltage values of some of the resistors.

或いは、第１、第２及び第３負荷抵抗に流れる電流に基づいて、絶縁抵抗ＲＬ及び地絡位置を求めてもよい。例えば、上記の例において、発電部１１の正極を第１負荷抵抗を介して接地した際に第１負荷抵抗に流れる電流を電流値Ｉ１とし、発電部１１の負極を第２負荷抵抗を介して接地した際に第２負荷抵抗に流れる電流を電流値Ｉ２とし、発電部１１の正極及び負極間を抵抗値ＲＤ３を有する第３負荷抵抗を介して互いに接続した際に第３負荷抵抗に流れる電流を電流値Ｉａとする場合、次式（Ｄ），（Ｅ）が成立し、また、ＲＤ３≦ＲＤ１、且つ、ＲＤ３≦ＲＤ２より、次式（Ｆ）が成立する。
Ｉ１＝Ｖ１／（ＲＬ＋ＲＤ１） …（Ｄ）
Ｉ２＝Ｖ２／（ＲＬ＋ＲＤ２） …（Ｅ）
Ｖ１+Ｖ２≧Ｖａ …（Ｆ） Alternatively, the insulation resistance RL and the ground fault position may be obtained based on currents flowing through the first, second, and third load resistors. For example, in the above example, the current flowing through the first load resistor and a current value I 1 of the positive electrode of the power generation unit 11 when the grounded via a first load resistor, via a negative electrode second load resistor of the power generation portion 11 the current flowing through the second load resistor and a current value I 2 upon grounded Te, third load resistor when the via third load resistor having a resistance value R D3 between the positive electrode and the negative electrode of the power generation unit 11 are connected to each other If the current value I a current flowing to the following formula (D), satisfied (E), also, R D3 ≦ R D1, and, from the R D3 ≦ R D2, the following equation (F) is satisfied .
I 1 = V 1 / (R L + R D1 ) (D)
I 2 = V 2 / (R L + R D2 ) (E)
V 1 + V 2 ≧ V a (F)

そして、上式（Ｄ），（Ｅ），（Ｆ）より、下式を得ることができる。
ＲＬ≧（Ｖａ−ＲＤ２×Ｉ２−ＲＤ１×Ｉ１）／（Ｉ１＋Ｉ２）
すなわち、Ｖ１＋Ｖ２＝Ｖａとみなし、また、Ｖａ＝ＲＤ３×Ｉａであることから、絶縁抵抗ＲＬを
（ＲＤ３×Ｉａ−ＲＤ２×Ｉ２−ＲＤ１×Ｉ１）／（Ｉ１＋Ｉ２）
として評価すれば、絶縁抵抗ＲＬの真値は当該評価値以上であることから、絶縁抵抗ＲＬの低下を見逃すことなく把握することが可能となる。 Then, the following equation can be obtained from the above equations (D), (E), and (F).
R L ≧ (V a −R D2 × I 2 −R D1 × I 1 ) / (I 1 + I 2 )
That is, since V 1 + V 2 = V a and V a = R D3 × I a , the insulation resistance R L is
(R D3 × I a −R D2 × I 2 −R D1 × I 1 ) / (I 1 + I 2 )
Since the true value of the insulation resistance RL is equal to or higher than the evaluation value, it is possible to grasp without missing the decrease in the insulation resistance RL .

さらにこの場合、下式により地絡位置を推定することが可能である。
Ｖ１：Ｖ２＝Ｉ１×（ＲＤ３×Ｉａ＋Ｉ２×（ＲＤ１−ＲＤ２））：
Ｉ２×（ＲＤ３×Ｉａ＋Ｉ１×（ＲＤ２−ＲＤ１）） Furthermore, in this case, it is possible to estimate the ground fault position by the following equation.
V 1 : V 2 = I 1 × (R D3 × I a + I 2 × (R D1 −R D2 )):
I 2 × (R D3 × I a + I 1 × (R D2 −R D1 ))

［第３実施形態］
次に、本発明の第３実施形態について説明する。本実施形態の説明では、上記第１実施形態と異なる点について主に説明する。 [Third Embodiment]
Next, a third embodiment of the present invention will be described. In the description of the present embodiment, differences from the first embodiment will be mainly described.

図６は、第３実施形態に係る絶縁抵抗測定装置を示す構成図である。図６に示すように、本実施形態の絶縁抵抗測定装置３００が上記第１実施形態と異なる点は、測定部１０（図１参照）に代えて、対地測定部３１１及び極間測定部３１２を有する測定部３１０を備えている点である。   FIG. 6 is a configuration diagram illustrating an insulation resistance measuring apparatus according to the third embodiment. As shown in FIG. 6, the insulation resistance measuring apparatus 300 of the present embodiment is different from the first embodiment in that a ground measuring unit 311 and an inter-electrode measuring unit 312 are used instead of the measuring unit 10 (see FIG. 1). It is the point provided with the measurement part 310 which has.

対地測定部３１１は、第１及び第２測定部を構成するものであり、抵抗３１と、この抵抗３１の電圧値を測定する双極型の電圧計３２と、切替えスイッチ３１９ａを介して電圧計３２の一方側を発電部１１の正極に接続する配線３３ｘと、切替えスイッチ３１９ｂを介して電圧計３２の一方側を発電部１１の正極に接続する配線３３ｙと、電圧計３２の他方側を大地Ｇに接続する配線３４と、を含んでいる。配線３３ｘには、抵抗３５ｘが設けられ、配線３３ｙには、抵抗３５ｙが設けられている。   The ground measurement unit 311 constitutes a first measurement unit and a second measurement unit, and includes a resistor 31, a bipolar voltmeter 32 that measures the voltage value of the resistor 31, and a voltmeter 32 via a changeover switch 319a. A wiring 33x that connects one side of the voltmeter 32 to the positive electrode of the power generation unit 11, a wiring 33y that connects one side of the voltmeter 32 to the positive electrode of the power generation unit 11 via the changeover switch 319b, and a ground G And a wiring 34 connected to the. The wiring 33x is provided with a resistor 35x, and the wiring 33y is provided with a resistor 35y.

極間測定部３１２は、第３測定部を構成するものであり、抵抗３６と、この抵抗３６の電圧値を測定する電圧計３７と、切替えスイッチ３１９ｃを介して電圧計３７の正極を発電部１１の正極に接続する配線３８と、切替えスイッチ３１９ｄを介して電圧計３７の負極を発電部１１の負極に接続する配線３９と、を含んでいる。   The inter-electrode measuring unit 312 constitutes a third measuring unit, and a resistor 36, a voltmeter 37 for measuring the voltage value of the resistor 36, and a positive electrode of the voltmeter 37 via a changeover switch 319c are generated as a power generation unit. 11, and a wiring 39 that connects the negative electrode of the voltmeter 37 to the negative electrode of the power generation unit 11 via the changeover switch 319 d.

ここで、本実施形態では、抵抗３１の抵抗値と抵抗３５ｘの抵抗値との合計、抵抗３１の抵抗値と抵抗３５ｙの抵抗値との合計、及び、抵抗３６の抵抗値が、互いに同じとされており、ここでは、所定抵抗値ＲＤとされている。これにより、本実施形態においても、第１負荷抵抗と第２負荷抵抗と第３負荷抵抗とが互いに同じ所定抵抗値ＲＤとなっており、よって、絶縁抵抗ＲＬを過大評価するおそれなく監視し、絶縁抵抗ＲＬの低下を見逃すことなく把握することが可能となるという上記作用効果が奏される。 In this embodiment, the sum of the resistance value of the resistor 31 and the resistance value of the resistor 35x, the sum of the resistance value of the resistor 31 and the resistance value of the resistor 35y, and the resistance value of the resistor 36 are the same. Here, the predetermined resistance value RD is used. As a result, also in the present embodiment, the first load resistance, the second load resistance, and the third load resistance have the same predetermined resistance value R D, and therefore, the insulation resistance R L can be monitored without overestimating. In addition, the above-described effect is achieved that it is possible to grasp without missing the decrease in the insulation resistance RL .

以上、本発明の好適な実施形態について説明したが、本発明は上記実施形態に限られるものではなく、各請求項に記載した要旨を変更しない範囲で変形し、又は他のものに適用したものであってもよい。   The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments. The present invention is modified without departing from the scope described in the claims or applied to others. It may be.

例えば、太陽電池モジュール１７を構成する太陽電池ユニットの数、太陽電池ストリング１８を構成する太陽電池モジュール１７の数、太陽電池アレイを構成する太陽電池ストリング１８の数、及び、太陽光発電システムを構成する太陽電池アレイの数については、限定されるものではなく、１つとしてもよいし複数としてもよい。   For example, the number of solar cell units constituting the solar cell module 17, the number of solar cell modules 17 constituting the solar cell string 18, the number of solar cell strings 18 constituting the solar cell array, and the photovoltaic power generation system are constituted. The number of solar cell arrays to be performed is not limited, and may be one or plural.

また、上記実施形態では、第１測定部により第１電圧値ＶＤ１を測定したが、電流値Ｉ１を測定してもよい。また、第２測定部により第２電圧値ＶＤ２を測定したが、電流値Ｉ２を測定してもよい。また、本発明においては、測定部の構成は限定されるものではなく、第１負荷抵抗と第２負荷抵抗と第３負荷抵抗とが互いに同じ所定抵抗値であれば、種々の構成を採用することができる。なお、上記実施形態は、絶縁抵抗測定装置を備えた太陽電池ストリング、太陽電池アレイ又は太陽光発電システムとして捉えることもできる。 In the above embodiment, the first measuring section was measured first voltage value V D1, may measure the current value I 1. Further, the second measuring section was measured second voltage value V D2, may measure the current value I 2. In the present invention, the configuration of the measurement unit is not limited, and various configurations may be employed as long as the first load resistance, the second load resistance, and the third load resistance have the same predetermined resistance value. be able to. In addition, the said embodiment can also be grasped | ascertained as a solar cell string provided with the insulation resistance measuring apparatus, a solar cell array, or a solar power generation system.

また、上記第１〜３実施形態の何れかに係る絶縁抵抗測定装置は、警報部を更に備えた絶縁監視装置として捉えることもできる。つまり、本発明は、絶縁抵抗測定装置１００，２００，３００の何れかを用いて発電部１１における絶縁抵抗を測定し、その測定結果である絶縁抵抗が所定値を下回っている場合に警報を発する絶縁監視装置として捉えることもできる。   Moreover, the insulation resistance measuring apparatus according to any of the first to third embodiments can also be regarded as an insulation monitoring apparatus further provided with an alarm unit. That is, the present invention measures the insulation resistance in the power generation unit 11 using any one of the insulation resistance measuring devices 100, 200, and 300, and issues an alarm when the insulation resistance that is the measurement result is below a predetermined value. It can also be understood as an insulation monitoring device.

この場合、例えば、警報部は、演算ユニット１６により演算された発電部１１の絶縁抵抗ＲＬを、記憶装置に予め記憶された所定値と比較し（比較判定処理）、絶縁抵抗ＲＬが所定値を下回っている場合に警報を発する。警報部としては、ブザー等の音を発するものであってもよいし、モニタに地絡がある旨を表示するものであってもよいし、別途設けられた監視システムに無線又は有線により警報信号を発信するものであってもよいし、これらの少なくとも何れかを有するものであってもよい。警報部の比較判定処理は、演算ユニット１６により実行する構成としてもよい。 In this case, for example, the alarm unit compares the insulation resistance RL of the power generation unit 11 calculated by the arithmetic unit 16 with a predetermined value stored in advance in the storage device (comparison determination process), and the insulation resistance RL is predetermined. Raise an alarm when below the value. The alarm unit may emit a sound such as a buzzer, may indicate that there is a ground fault on the monitor, or alarm signal by wireless or wired to a separate monitoring system. May be transmitted, or at least one of these may be included. The comparison determination process of the alarm unit may be executed by the arithmetic unit 16.

なお、「発電部１１の正極と大地Ｇとの接続」、「発電部１１の負極と大地Ｇとの接続」、「発電部１１の正極と負極との接続」、「電圧計１２の負極と大地Ｇとの接続」、「電圧計１２の正極と発電部１１の正極との接続」、「電圧計１２の正極と大地Ｇとの接続」、「電圧計１２の負極と発電部１１の負極との接続」、及び、「電圧計１２の負極と大地Ｇとの接続」のそれぞれでは、接続される両者の間に１又は複数の抵抗やスイッチ等の電子部品（素子）が介在されていてもよく、要は、両者が互いに電気的に接続されていればよい。   “Connection between positive electrode of power generation unit 11 and ground G”, “Connection between negative electrode of power generation unit 11 and ground G”, “Connection between positive electrode and negative electrode of power generation unit 11”, “Negative electrode of voltmeter 12” "Connection with the ground G", "Connection between the positive electrode of the voltmeter 12 and the positive electrode of the power generation unit 11", "Connection between the positive electrode of the voltmeter 12 and the ground G", "Negative electrode of the voltmeter 12 and the negative electrode of the power generation unit 11" And “connection between the negative electrode of the voltmeter 12 and the ground G”, one or more electronic components (elements) such as resistors and switches are interposed between the two connected. In short, it is only necessary that both are electrically connected to each other.

１０，２１０，３１０…測定部、１１…発電部、１２…電圧計（第１測定部，第２測定部，第３測定部）、１２ａ…抵抗（第１測定部，第２測定部，第３測定部）、１３…第１切替接続部（第１測定部，第２測定部，第３測定部）、１４…第２切替接続部（第１測定部，第２測定部，第３測定部）、１６…演算ユニット（演算部）、１７…太陽電池モジュール、１８…太陽電池ストリング、１９ａ…切替えスイッチ（第１測定部，第３測定部）１９ｂ…切替えスイッチ（第２測定部）、１９ｃ…切替えスイッチ（第２測定部，第３測定部）、１９ｄ…切替えスイッチ（第１測定部）、１００，２００，３００…絶縁抵抗測定装置、２１１…第１測定部、２１２…第２測定部、２１３…第３測定部、３１１…対地測定部（第１測定部，第２測定部）、３１２…極間測定部（第３測定部）、Ｇ…大地。   DESCRIPTION OF SYMBOLS 10,210,310 ... Measurement part, 11 ... Electric power generation part, 12 ... Voltmeter (1st measurement part, 2nd measurement part, 3rd measurement part), 12a ... Resistance (1st measurement part, 2nd measurement part, 1st 3 measurement unit), 13 ... first switching connection unit (first measurement unit, second measurement unit, third measurement unit), 14 ... second switching connection unit (first measurement unit, second measurement unit, third measurement) Part), 16 ... arithmetic unit (arithmetic part), 17 ... solar cell module, 18 ... solar cell string, 19a ... changeover switch (first measurement part, third measurement part) 19b ... changeover switch (second measurement part), 19c ... changeover switch (second measurement unit, third measurement unit), 19d ... changeover switch (first measurement unit), 100, 200, 300 ... insulation resistance measuring device, 211 ... first measurement unit, 212 ... second measurement , 213... Third measurement unit, 311... Ground measurement unit (first measurement unit, second measurement. ), 312 ... interpolar measuring section (third measuring unit), G ... earth.

Claims (7)

少なくとも一つの太陽電池モジュールにより構成された発電部における絶縁抵抗を測定するための絶縁抵抗測定装置であって、
前記発電部の正極を大地に接続させた状態で、該正極及び大地間の第１負荷抵抗における電圧値又は電流値を測定する第１測定部と、
前記発電部の負極を大地に接地させた状態で、該負極及び大地間の第２負荷抵抗における電圧値又は電流値を測定する第２測定部と、
前記発電部の正極及び負極を互いに接続させた状態で、該正極及び該負極間の第３負荷抵抗における電圧値又は電流値を測定する第３測定部と、を備えた測定部を具備し、
前記第３負荷抵抗の抵抗値は、
前記第１及び第２負荷抵抗が同じ抵抗値を有する場合、当該抵抗値以下とされ、
前記第１及び第２負荷抵抗が互いに異なる抵抗値を有する場合、前記第１及び第２負荷抵抗の各抵抗値のうち小さい一方の抵抗値以下とされていること、を特徴とする絶縁抵抗測定装置。 An insulation resistance measuring device for measuring an insulation resistance in a power generation unit constituted by at least one solar cell module,
A first measurement unit for measuring a voltage value or a current value in a first load resistance between the positive electrode and the ground in a state where the positive electrode of the power generation unit is connected to the ground;
A second measuring unit for measuring a voltage value or a current value in a second load resistance between the negative electrode and the ground in a state where the negative electrode of the power generation unit is grounded to the ground;
A third measurement unit that measures a voltage value or a current value at a third load resistance between the positive electrode and the negative electrode in a state where the positive electrode and the negative electrode of the power generation unit are connected to each other;
The resistance value of the third load resistor is
When the first and second load resistors have the same resistance value, the resistance value is equal to or less than the resistance value,
Insulation resistance measurement, wherein when the first and second load resistors have different resistance values, the resistance value is less than one of the resistance values of the first and second load resistors. apparatus. 下式（１−１）に基づいて前記絶縁抵抗ＲＬを演算する演算部を備えたこと、を特徴とする請求項１記載の絶縁抵抗測定装置。
ＲＬ≧（ＲＤ３×Ｉａ−ＲＤ２×Ｉ２−ＲＤ１×Ｉ１）／（Ｉ１＋Ｉ２）…（１−１）
但し、Ｉ１：前記発電部の正極を大地に接続させた状態での前記第１負荷抵抗における電流値、Ｉ２：前記発電部の負極を大地に接続させた状態での前記第２負荷抵抗における電流値、Ｉａ：前記発電部の正極及び負極を互いに接続させた状態での前記第３負荷抵抗における電流値、ＲＤ１：前記第１負荷抵抗、ＲＤ２：前記第２負荷抵抗、ＲＤ３：前記第３負荷抵抗、ＲＬ：前記絶縁抵抗。 The insulation resistance measuring apparatus according to claim 1, further comprising a calculation unit that calculates the insulation resistance RL based on the following formula (1-1).
R L ≧ (R D3 × I a −R D2 × I 2 −R D1 × I 1 ) / (I 1 + I 2 ) (1-1)
Where I 1 is the current value in the first load resistance when the positive electrode of the power generation unit is connected to the ground, and I 2 is the second load resistance when the negative electrode of the power generation unit is connected to the ground. Current value at Ia : current value at the third load resistance in a state where the positive electrode and the negative electrode of the power generation unit are connected to each other, R D1 : the first load resistance, R D2 : the second load resistance, R D3 : the third load resistance, R L : the insulation resistance. 下式（１−２）に基づいて地絡点の位置を演算する演算部を備えたこと、を特徴とする請求項１又は２記載の絶縁抵抗測定装置。
Ｖ１：Ｖ２＝Ｉ１×（ＲＤ３×Ｉａ＋Ｉ２×（ＲＤ１−ＲＤ２））：
Ｉ２×（ＲＤ３×Ｉａ＋Ｉ１×（ＲＤ２−ＲＤ１））…（１−２）
但し、Ｖ１：地絡点から発電部の正極までの電圧値、Ｖ２：地絡点から発電部の負極までの電圧値、Ｉ１：前記発電部の正極を大地に接続させた状態での前記第１負荷抵抗における電流値、Ｉ２：前記発電部の負極を大地に接続させた状態での前記第２負荷抵抗における電流値、ＲＤ１：前記第１負荷抵抗、ＲＤ２：前記第２負荷抵抗、ＲＤ３：前記第３負荷抵抗。 The insulation resistance measuring apparatus according to claim 1, further comprising a calculation unit that calculates the position of the ground fault point based on the following equation (1-2).
V 1 : V 2 = I 1 × (R D3 × I a + I 2 × (R D1 −R D2 )):
I 2 × (R D3 × I a + I 1 × (R D2 −R D1 )) (1-2)
Where V 1 is the voltage value from the ground fault point to the positive electrode of the power generation unit, V 2 is the voltage value from the ground fault point to the negative electrode of the power generation unit, and I 1 is the state where the positive electrode of the power generation unit is connected to the ground. Current value in the first load resistance, I 2 : current value in the second load resistance with the negative electrode of the power generation unit connected to the ground, R D1 : the first load resistance, R D2 : the first 2 load resistance, R D3 : the third load resistance. 前記第１、第２及び第３負荷抵抗は、互いに同じ所定抵抗値を有すること、を特徴とする請求項１〜３の何れか一項記載の絶縁抵抗測定装置。   The said 1st, 2nd and 3rd load resistance has the mutually same predetermined resistance value, The insulation resistance measuring apparatus as described in any one of Claims 1-3 characterized by the above-mentioned. 前記測定部は、
正極及び負極を有し、該正極及び該負極間の抵抗の電圧値を測定する電圧計と、
前記電圧計の正極を、前記発電部の正極と大地との間で切替可能に接続する第１切替接続部と、
前記電圧計の負極を、前記発電部の負極と大地との間で切替可能に接続する第２切替接続部と、を含んで構成され、
前記第１、第２及び第３負荷抵抗は、前記電圧計の正極及び負極間の前記抵抗により構成されており、
前記第１測定部は、前記第１切替接続部によって前記電圧計の正極を前記発電部の正極に接続させつつ、前記第２切替接続部によって前記電圧計の負極を大地に接続させた状態で、前記抵抗における電圧値又は電流値を測定し、
前記第２測定部は、前記第１切替接続部によって前記電圧計の正極を大地に接続させつつ、前記第２切替接続部によって前記電圧計の負極を前記発電部の負極に接続させた状態で、前記抵抗における電圧値又は電流値を測定し、
前記第３測定部は、前記第１切替接続部によって前記電圧計の正極を前記発電部の正極に接続させつつ、前記第２切替接続部によって前記電圧計の負極を前記発電部の負極に接続させた状態で、前記抵抗における電圧値又は電流値を測定すること、を特徴とする請求項２〜４の何れか一項記載の絶縁抵抗測定装置。 The measuring unit is
A voltmeter having a positive electrode and a negative electrode and measuring a voltage value of a resistance between the positive electrode and the negative electrode;
A first switching connection portion that connects the positive electrode of the voltmeter in a switchable manner between the positive electrode of the power generation unit and the ground; and
A second switching connection portion that connects the negative electrode of the voltmeter in a switchable manner between the negative electrode of the power generation unit and the ground, and
The first, second and third load resistors are constituted by the resistance between the positive electrode and the negative electrode of the voltmeter,
The first measurement unit is configured to connect the negative electrode of the voltmeter to the ground by the second switching connection unit while connecting the positive electrode of the voltmeter to the positive electrode of the power generation unit by the first switching connection unit. , Measure the voltage value or current value in the resistor,
The second measurement unit is configured to connect the positive electrode of the voltmeter to the ground through the first switching connection unit and connect the negative electrode of the voltmeter to the negative electrode of the power generation unit through the second switching connection unit. , Measure the voltage value or current value in the resistor,
The third measuring unit connects the positive electrode of the voltmeter to the positive electrode of the power generation unit by the first switching connection unit, and connects the negative electrode of the voltmeter to the negative electrode of the power generation unit by the second switching connection unit. The insulation resistance measuring device according to any one of claims 2 to 4, wherein a voltage value or a current value in the resistor is measured in a state where the resistance is set. 請求項１〜５の何れか一項記載の絶縁抵抗測定装置を用いて前記発電部における前記絶縁抵抗を測定すること、特徴とする絶縁抵抗測定方法。   An insulation resistance measuring method, comprising: measuring the insulation resistance in the power generation unit using the insulation resistance measuring device according to any one of claims 1 to 5. 請求項１〜６の何れか一項記載の絶縁抵抗測定装置を用いて前記発電部における前記絶縁抵抗を測定し、測定した前記絶縁抵抗が所定値を下回っている場合に、警報を発することを特徴とする絶縁監視装置。   The insulation resistance measuring device according to any one of claims 1 to 6 is used to measure the insulation resistance in the power generation unit, and when the measured insulation resistance is below a predetermined value, an alarm is issued. Characteristic insulation monitoring device.
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