WO2021213211A1

WO2021213211A1 - Cable insulation impedance detection method and device

Info

Publication number: WO2021213211A1
Application number: PCT/CN2021/086772
Authority: WO
Inventors: 王勋
Original assignee: 华为技术有限公司
Priority date: 2020-04-20
Filing date: 2021-04-13
Publication date: 2021-10-28
Also published as: CN111610411A

Abstract

A cable insulation impedance detection method and device. The method is executed by an inverter, and the output of the inverter is connected to a plurality of alternating current cables. The method comprises: disconnecting an alternating current cable to be inspected in the plurality of alternating current cables from a direct current bus of the inverter, and executing a direct current side ground insulation impedance detection procedure so as to obtain a first impedance Riso1 by means of detection (S301); electrically connecting the alternating current cable to be inspected to the positive pole or the negative pole of the direct current bus, and executing the direct current side ground insulation impedance detection procedure, so as to obtain a second impedance Riso2 by means of detection (S302); and determining, according to Riso1 and Riso2, the ground insulation impedance of the alternating current cable to be inspected (S303). Automatic detection of the ground insulation resistance of an alternating current side cable is achieved by means of the inverter, the application safety is improved, and the cable construction inspection cost is reduced.

Description

线缆绝缘阻抗检测方法和装置Cable insulation resistance detection method and device

本申请要求于2020年04月20日提交中国国家知识产权局、申请号为202010309709.5、申请名称为“线缆绝缘阻抗检测方法和装置”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。This application claims the priority of a Chinese patent application filed with the State Intellectual Property Office of China, the application number is 202010309709.5, and the application name is "Method and Device for Testing Cable Insulation Resistance" on April 20, 2020, the entire content of which is incorporated by reference In this application.

技术领域Technical field

本申请涉及电路领域，更具体地，涉及一种线缆绝缘阻抗检测方法和装置。This application relates to the field of circuits, and more specifically, to a method and device for detecting cable insulation resistance.

背景技术Background technique

目前大型光伏电站一般通过光伏组件串联接入逆变器。多个逆变器的输出端通过线缆接到箱变低压柜中的塑壳断路器(molded case circuit breaker，MCCB)里面，逆变器输出端线缆通常为地沟的方式布线，在布线过程中容易出现线缆破皮，相间短路或者相对地阻抗异常，导致交流上电合MCCB断路器时，大的短路电流易导致MCCB开关喷弧甚至烧毁，需要现场检修。At present, large-scale photovoltaic power plants generally connect inverters in series through photovoltaic modules. The output terminals of multiple inverters are connected to the molded case circuit breaker (MCCB) in the low-voltage cabinet of the box substation through cables. The cables of the inverter output terminals are usually wired in a trench. When the MCCB circuit breaker is switched on and the MCCB circuit breaker is closed, the large short circuit current can easily cause the MCCB switch to arc or even burn out, requiring on-site inspection and repair.

现有解决方法是在施工人员布好线缆后，专业技术人员采用摇表的方式对交流侧线缆进行绝缘阻抗测试，安全性低，线缆施工检测成本高。The existing solution is that after the construction workers have laid out the cables, the professional and technical personnel use the meter-shaking method to test the insulation impedance of the AC-side cables, which has low safety and high cable construction and detection costs.

发明内容Summary of the invention

本申请提供一种线缆绝缘阻抗检测方法和装置，通过逆变器实现交流侧线缆对地绝缘阻抗自动检测，提高应用安全性，降低线缆施工检测成本。The present application provides a cable insulation resistance detection method and device, which realizes automatic detection of the AC side cable insulation resistance to the ground through an inverter, improves application safety, and reduces cable construction detection costs.

第一方面，提供了一种线缆绝缘阻抗检测方法，该方法由逆变器执行，逆变器的输出电连接至多条交流线缆，该方法包括：将多条交流线缆中的待测交流线缆与逆变器的直流母线断开，并执行直流侧对地绝缘阻抗程序，以检测得到第一阻抗Riso1；将待测交流线缆与直流母线的正极或负极电连通，并执行直流侧对地绝缘阻抗程序，以检测得到第二阻抗Riso2；根据Riso1和Riso2，确定待测交流线缆的对地绝缘阻抗。In a first aspect, a method for detecting cable insulation resistance is provided. The method is executed by an inverter, and the output of the inverter is electrically connected to a plurality of AC cables. The method includes: The AC cable is disconnected from the DC bus of the inverter, and the DC side-to-ground insulation impedance program is executed to detect the first impedance Riso1; the AC cable to be tested is electrically connected to the positive or negative pole of the DC bus, and the DC The side-to-ground insulation resistance program is used to detect the second impedance Riso2; according to Riso1 and Riso2, the ground insulation resistance of the AC cable to be tested is determined.

本申请实施例提供的线缆绝缘阻抗检测方法，根据现有的逆变器和电路，实现交流侧线缆对地绝缘阻抗自动检测，同时无需使用或增加任何额外的装置，避免人工检测，提高应用安全性，降低线缆施工检测成本。The cable insulation resistance detection method provided by the embodiments of the present application realizes automatic detection of the insulation resistance of the AC side cable to the ground based on the existing inverter and circuit, and at the same time, it does not need to use or add any additional devices, avoid manual detection, and improve Application safety reduces the cost of cable construction and inspection.

结合第一方面，在第一方面的某些实现方式中，待测交流线缆为对应于逆变器的一相输出的交流线缆，其中，第二阻抗Riso2为Riso1//R3，其中//表示阻抗并运算，R3为待测交流线缆的对地绝缘阻抗，根据Riso1和Riso2，确定待测交流线缆的对地绝缘阻抗，包括：根据如下方式计算R3：R3＝Riso1ⅹRiso2/(Riso1-Riso2)。With reference to the first aspect, in some implementations of the first aspect, the AC cable to be tested is an AC cable corresponding to one-phase output of the inverter, where the second impedance Riso2 is Riso1//R3, where / / Represents the impedance and calculate it, R3 is the insulation resistance to the ground of the AC cable to be tested. Determine the insulation resistance to the ground of the AC cable to be tested according to Riso1 and Riso2, including: Calculate R3 according to the following method: R3=Riso1ⅹRiso2/(Riso1 -Riso2).

结合第一方面，在第一方面的某些实现方式中，待测交流线缆为对应于逆变器的两相输出的两条交流线缆，其中，第二阻抗Riso2为Riso1//R3//R4，其中//表示阻抗并运算，R3为两条交流线缆中一条交流线缆的对地绝缘阻抗，R4为两条交流线缆中另一条交流线缆的对地绝缘阻抗，根据Riso1和Riso2，确定待测交流线缆的对地绝缘阻抗，包括：根据如下方式计算两条交流线缆的总的对地绝缘阻抗R3//R4：R3//R4＝Riso1*Riso2/(Riso1-Riso2)。In combination with the first aspect, in some implementations of the first aspect, the AC cables to be tested are two AC cables corresponding to the two-phase output of the inverter, and the second impedance Riso2 is Riso1//R3/ /R4, where // represents impedance and operation, R3 is the insulation resistance to ground of one of the two AC cables, and R4 is the insulation resistance to ground of the other of the two AC cables, according to Riso1 And Riso2, determine the insulation resistance to ground of the AC cable under test, including: calculate the total insulation resistance to ground R3//R4 of the two AC cables according to the following method: R3//R4=Riso1*Riso2/(Riso1- Riso2).

结合第一方面，在第一方面的某些实现方式中，待测交流线缆为对应于逆变器的三相输出的三条交流线缆，其中，第二阻抗Riso2为Riso1//R3//R4//R5，其中//表示阻抗并运算，R3、R4、R5分别为三条交流线缆中每条交流线缆的对地绝缘阻抗，根据Riso1和Riso2，确定待测交流线缆的对地绝缘阻抗，包括：根据如下方式计算三条交流线缆的总的对地绝缘阻抗R3//R4//R5：R3//R4//R5＝Riso1*Riso2/(Riso1-Riso2)。In combination with the first aspect, in some implementations of the first aspect, the AC cables to be tested are three AC cables corresponding to the three-phase output of the inverter, where the second impedance Riso2 is Riso1//R3// R4//R5, where // represents impedance and calculation, R3, R4, and R5 are the insulation resistance of each of the three AC cables to the ground. According to Riso1 and Riso2, determine the grounding of the AC cable to be tested The insulation resistance includes: Calculate the total insulation resistance R3//R4//R5 of the three AC cables according to the following method: R3//R4//R5=Riso1*Riso2/(Riso1-Riso2).

本申请实施例提供的线缆绝缘阻抗检测方法，根据简单的运算，不仅可以检测单相线缆的对地绝缘阻抗，还可以检测两相甚至更多相线缆的总对地绝缘阻抗，应用范围广。The cable insulation resistance detection method provided by the embodiments of the present application can not only detect the insulation resistance to ground of a single-phase cable, but also detect the total insulation resistance to ground of two-phase or more phase cables based on simple calculations. wide range.

结合第一方面，在第一方面的某些实现方式中，在检测得到第一阻抗Riso1之后，还包括：确定Riso1大于或等于第一阈值。With reference to the first aspect, in some implementation manners of the first aspect, after the first impedance Riso1 is detected, the method further includes: determining that Riso1 is greater than or equal to the first threshold.

本申请实施例提供的线缆绝缘阻抗检测方法，在进行第一步检测之后对Riso1进行判断，若确定Riso1小于第一阈值，则生成告警信息，无需再进行后续检测，节约检测成本。In the cable insulation resistance detection method provided by the embodiment of the present application, Riso1 is judged after the first step of detection, and if it is determined that Riso1 is less than the first threshold, alarm information is generated, and subsequent detection is not required, which saves the cost of detection.

结合第一方面，在第一方面的某些实现方式中，还包括：若待测交流线缆的对地绝缘阻抗值小于第二阈值，则生成告警信息；或者若待测交流线缆对地绝缘阻抗值大于或等于第二阈值，则生成表示待测交流线缆对地绝缘阻抗值正常的信息。In combination with the first aspect, in some implementations of the first aspect, the method further includes: generating an alarm message if the insulation resistance value of the AC cable to be tested is less than the second threshold; or if the AC cable to be tested is connected to the ground If the insulation resistance value is greater than or equal to the second threshold value, information indicating that the insulation resistance value of the AC cable to be tested to the ground is normal is generated.

本申请实施例提供的线缆绝缘阻抗检测方法，还包括对检测出的线缆绝缘阻抗进行判断，可以实现自动线缆状态的自动报告。The cable insulation resistance detection method provided by the embodiment of the present application further includes judging the detected cable insulation resistance, which can realize automatic reporting of automatic cable status.

第二方面，提供了一种线缆绝缘阻抗检测方法，该方法由逆变器执行，逆变器的输出通过并网开关电连接至交流线缆，该方法包括：导通交流线缆中任意两相交流线缆对应的并网开关，并对两相交流线缆中的第一相交流线缆对应的第一滤波电容充电；以第一滤波电容作为激励源，对两相交流线缆中的第二相交流线缆对应的第二滤波电容充电；检测第一滤波电容和第二滤波电容上的电压；根据第一滤波电容和第二滤波电容上的电压，确定两相交流线缆之间的相间绝缘阻抗。In a second aspect, a cable insulation resistance detection method is provided. The method is executed by an inverter. The output of the inverter is electrically connected to an AC cable through a grid-connected switch. The method includes: conducting any of the AC cables The grid-connected switch corresponding to the two-phase AC cable and charges the first filter capacitor corresponding to the first-phase AC cable in the two-phase AC cable; the first filter capacitor is used as the excitation source for the two-phase AC cable The second filter capacitor corresponding to the second-phase AC cable is charged; the voltage on the first filter capacitor and the second filter capacitor is detected; the voltage on the first filter capacitor and the second filter capacitor is used to determine which of the two-phase AC cables is Insulation resistance between phases.

本申请实施例不仅提供单相或多相线缆的对地绝缘阻抗的检测，还提供两相线缆之间的相间绝缘阻抗的检测，同样可以实现绝缘阻抗自动检测，同时无需使用或增加任何额外的装置，避免人工检测，提高应用安全性，降低线缆施工检测成本。The embodiments of the present application not only provide the detection of the insulation resistance to ground of single-phase or multi-phase cables, but also provide the detection of the insulation resistance between phases of two-phase cables. It can also realize the automatic detection of insulation resistance without using or adding anything. The additional device avoids manual inspection, improves application safety, and reduces the cost of cable construction inspection.

结合第二方面，在第二方面的某些实现方式中，确定两相交流线缆之间的相间绝缘阻抗包括：按照如下方式确定所述相间绝缘阻抗：-t/(Cbⅹln(1-Ub/Ua))，其中，t为对第二滤波电容充电的时间，Cb为第二滤波电容值，Ub为第二滤波电容上的电压，Ua为第一滤波电容上的电压；或者，按照如下方式确定相间绝缘阻抗：根据第一滤波电容上的电压、第二滤波电容上的电压和漏电流传感器检测的电流I确述相间绝缘阻抗。With reference to the second aspect, in some implementations of the second aspect, determining the phase-to-phase insulation resistance between two-phase AC cables includes: determining the phase-to-phase insulation resistance as follows: -t/(Cbⅹln(1-Ub/ Ua)), where t is the time to charge the second filter capacitor, Cb is the second filter capacitor value, Ub is the voltage on the second filter capacitor, and Ua is the voltage on the first filter capacitor; or, as follows Determine the insulation resistance between phases: Determine the insulation resistance between phases according to the voltage on the first filter capacitor, the voltage on the second filter capacitor and the current I detected by the leakage current sensor.

本申请实施例提供的线缆绝缘阻抗检测方法，基于简单的运算，并且可以通过多种计算方式得到线缆绝缘阻抗，选择多样。The cable insulation resistance detection method provided by the embodiments of the present application is based on simple calculations, and the cable insulation resistance can be obtained through various calculation methods, with various options.

结合第二方面，在第二方面的某些实现方式中，在对两相交流线缆中的第一相交流线缆对应的第一滤波电容充电之前，该方法还包括：控制逆变器的直流母线的电压值大于或等于电网线电压不控整流值。With reference to the second aspect, in some implementations of the second aspect, before charging the first filter capacitor corresponding to the first phase AC cable in the two-phase AC cable, the method further includes: controlling the inverter The voltage value of the DC bus is greater than or equal to the uncontrolled rectification value of the grid line voltage.

本申请实施例还提供了一种检测过程中对逆变器保护的方法。在该步骤中如果误闭合 MCCB，可能造成逆变器损坏，为规避风险，需要控制逆变器的直流母线的电压值大于或等于电网线电压不控整流值。The embodiment of the present application also provides a method for protecting the inverter during the detection process. In this step, if the MCCB is closed by mistake, the inverter may be damaged. To avoid risks, it is necessary to control the voltage value of the inverter's DC bus to be greater than or equal to the uncontrolled rectification value of the grid line voltage.

结合第二方面，在第二方面的某些实现方式中，还包括：若相间绝缘阻抗值小于第三阈值，则生成告警信息；或者，若相间绝缘阻抗值大于或等于第三阈值，则生成表示相间绝缘阻抗值正常的信息。With reference to the second aspect, in some implementations of the second aspect, it further includes: if the interphase insulation resistance value is less than the third threshold, generating alarm information; or, if the interphase insulation resistance value is greater than or equal to the third threshold, generating It indicates that the insulation resistance value between phases is normal.

第三方面，提供了一种线缆绝缘阻抗检测装置，该装置置于逆变器中，逆变器的输出电连接至多条交流线缆，该装置包括：控制器，用于控制将多条交流线缆中的待测交流线缆与逆变器的直流母线断开，并执行直流侧对地绝缘阻抗程序，根据检测电路检测结果计算得到第一阻抗Riso1；控制器还用于控制将待测交流线缆与直流母线的正极或负极电连通，并执行直流侧对地绝缘阻抗检测程序，根据检测电路检测结果计算得到第二阻抗Riso2；该控制器还用于根据Riso1和Riso2，确定待测交流线缆的对地绝缘阻抗。In a third aspect, a cable insulation resistance detection device is provided. The device is placed in an inverter, and the output of the inverter is electrically connected to a plurality of AC cables. The device includes: a controller for controlling the The AC cable to be tested in the AC cable is disconnected from the DC bus of the inverter, and the DC side insulation impedance program to ground is executed, and the first impedance Riso1 is calculated according to the detection result of the detection circuit; the controller is also used to control the Measure the electrical connection between the AC cable and the positive or negative pole of the DC bus, and execute the DC side-to-earth insulation impedance detection program, and calculate the second impedance Riso2 according to the detection circuit detection results; the controller is also used to determine the pending resistance according to Riso1 and Riso2. Measure the insulation resistance of AC cables to ground.

结合第三方面，在第三方面的某些实现方式中，待测交流线缆为对应于逆变器的一相输出的交流线缆，其中，第二阻抗Riso2为Riso1//R3，其中//表示阻抗并运算，R3为待测交流线缆的对地绝缘阻抗，根据所述Riso1和所述Riso2，确定待测交流线缆的对地绝缘阻抗，包括：根据如下方式计算R3：R3＝Riso1ⅹRiso2/(Riso1-Riso2)。With reference to the third aspect, in some implementations of the third aspect, the AC cable to be tested is an AC cable corresponding to the one-phase output of the inverter, where the second impedance Riso2 is Riso1//R3, where / / Represents the impedance and calculate it, R3 is the insulation resistance to ground of the AC cable to be tested. According to the Riso1 and the Riso2, the insulation resistance to ground of the AC cable to be tested is determined, including: calculating R3 according to the following method: R3= Riso1ⅹRiso2/(Riso1-Riso2).

结合第三方面，在第三方面的某些实现方式中，待测交流线缆为对应于逆变器的两相输出的两条交流线缆，其中，第二阻抗Riso2为Riso1//R3//R4，其中//表示阻抗并运算，R3为两条交流线缆中一条交流线缆的对地绝缘阻抗，R4为两条交流线缆中另一条交流线缆的对地绝缘阻抗，根据所述Riso1和所述Riso2，确定待测交流线缆的对地绝缘阻抗，包括：根据如下方式计算两条交流线缆的总的对地绝缘阻抗R3//R4：R3//R4＝Riso1*Riso2/(Riso1-Riso2)。In combination with the third aspect, in some implementations of the third aspect, the AC cables to be tested are two AC cables corresponding to the two-phase output of the inverter, where the second impedance Riso2 is Riso1//R3/ /R4, where // represents impedance and operation, R3 is the insulation resistance to ground of one of the two AC cables, and R4 is the insulation resistance to ground of the other of the two AC cables. The Riso1 and Riso2 are used to determine the insulation resistance to ground of the AC cable to be tested, including: calculating the total insulation resistance to ground R3//R4 of the two AC cables according to the following method: R3//R4=Riso1*Riso2 /(Riso1-Riso2).

结合第三方面，在第三方面的某些实现方式中，在根据检测电路检测检测结果计算得到第一阻抗Riso1之后，还包括：确定Riso1大于或等于第一阈值。With reference to the third aspect, in some implementation manners of the third aspect, after the first impedance Riso1 is calculated according to the detection result of the detection circuit, the method further includes: determining that Riso1 is greater than or equal to the first threshold.

结合第三方面，在第三方面的某些实现方式中，还包括：若待测交流线缆的对地绝缘阻抗值小于第二阈值，则生成告警信息；或者若待测交流线缆对地绝缘阻抗值大于或等于第二阈值，则生成表示待测交流线缆对地绝缘阻抗值正常的信息。In combination with the third aspect, in some implementations of the third aspect, the method further includes: generating an alarm message if the insulation resistance value of the AC cable to be tested is less than the second threshold; or if the AC cable to be tested is connected to the ground If the insulation resistance value is greater than or equal to the second threshold value, information indicating that the insulation resistance value of the AC cable to be tested to the ground is normal is generated.

第四方面，提供了一种线缆绝缘阻抗检测装置，该装置置于逆变器中，逆变器的输出电连接至交流线缆，该装置包括：控制器，用于控制交流线缆中任意两相交流线缆对应的并网开关导通，并控制两相交流线缆中的第一相交流线缆对应的第一滤波电容充电；控制器还用于控制第一滤波电容作为激励源，对两相交流线缆中的第二相交流线缆对应的第二滤波电容充电；检测电路，用于检测第一滤波电容和第二滤波电容上的电压；该控制器还用于根据第一滤波电容和第二滤波电容上的电压，确定两相交流线缆之间的相间绝缘阻抗。In a fourth aspect, a cable insulation resistance detection device is provided, the device is placed in an inverter, the output of the inverter is electrically connected to an AC cable, and the device includes: a controller for controlling the AC cable The grid-connected switch corresponding to any two-phase AC cable is turned on and controls the charging of the first filter capacitor corresponding to the first phase of the two-phase AC cable; the controller is also used to control the first filter capacitor as an excitation source , To charge the second filter capacitor corresponding to the second phase of the two-phase AC cable; the detection circuit is used to detect the voltage on the first filter capacitor and the second filter capacitor; the controller is also used to The voltage on a filter capacitor and a second filter capacitor determines the phase-to-phase insulation impedance between the two-phase AC cables.

结合第四方面，在第四方面的某些实现方式中，确定两相交流线缆之间的相间绝缘阻抗包括：按照如下方式确定相间绝缘阻抗：-t/(Cbⅹln(1-Ub/Ua))，其中，t为对第二滤波电容充电的时间，Cb为第二滤波电容值，Ub为第二滤波电容上的电压，Ua为第一滤波电容上的电压；或者，按照如下方式确定所述相间绝缘阻抗：根据第一滤波电容上的电压、第二滤波电容上的电压和漏电流传感器检测的电流I确定。In combination with the fourth aspect, in some implementations of the fourth aspect, determining the phase-to-phase insulation resistance between two-phase AC cables includes: determining the phase-to-phase insulation resistance as follows: -t/(Cbⅹln(1-Ub/Ua) ), where t is the time to charge the second filter capacitor, Cb is the second filter capacitor value, Ub is the voltage on the second filter capacitor, and Ua is the voltage on the first filter capacitor; or, determine the value as follows The insulation resistance between phases is determined according to the voltage on the first filter capacitor, the voltage on the second filter capacitor and the current I detected by the leakage current sensor.

结合第四方面，在第四方面的某些实现方式中，在控制器控制两相交流线缆中的第一相交流线缆对应的第一滤波电容充电之前，还包括：控制逆变器的直流母线的电压值大于或等于电网线电压不控整流值。With reference to the fourth aspect, in some implementations of the fourth aspect, before the controller controls the charging of the first filter capacitor corresponding to the first phase AC cable in the two-phase AC cable, the method further includes: controlling the inverter The voltage value of the DC bus is greater than or equal to the uncontrolled rectification value of the grid line voltage.

结合第四方面，在第四方面的某些实现方式中，还包括：若相间绝缘阻抗值小于第三阈值，则生成告警信息；或者，若相间绝缘阻抗值大于或等于第三阈值，则生成表示相间绝缘阻抗值正常的信息。With reference to the fourth aspect, in some implementations of the fourth aspect, it further includes: generating an alarm message if the interphase insulation resistance value is less than the third threshold; or, if the interphase insulation resistance value is greater than or equal to the third threshold, generating It indicates that the insulation resistance value between phases is normal.

第五方面，提供了一种逆变器，包括控制单元，该控制单元用于实现上述第一方面和第一方面任意一种实现方式以及上述第二方面和第二方面任意一种实现方式中的方法。In a fifth aspect, an inverter is provided, including a control unit configured to implement any one of the foregoing first aspect and the first aspect and any one of the foregoing second aspect and the second aspect. Methods.

附图说明Description of the drawings

图1是本申请实施例提供的集中式架构的示意性结构图；FIG. 1 is a schematic structural diagram of a centralized architecture provided by an embodiment of the present application;

图2是本申请实施例提供的交流线缆绝缘阻抗摇表检测示意图；Figure 2 is a schematic diagram of AC cable insulation resistance testing provided by an embodiment of the present application;

图3是本申请实施例提供的一种线缆绝缘阻抗检测方法的流程图；FIG. 3 is a flowchart of a method for detecting cable insulation resistance according to an embodiment of the present application;

图4是本申请实施例提供的一种线缆绝缘阻抗检测方法的示意性框图；FIG. 4 is a schematic block diagram of a method for detecting cable insulation resistance according to an embodiment of the present application;

图5是本申请实施例提供的另一种线缆绝缘阻抗检测方法的流程图；FIG. 5 is a flowchart of another method for detecting cable insulation resistance according to an embodiment of the present application;

图6是本申请实施例提供的另一种线缆绝缘阻抗检测方法的示意性框图；FIG. 6 is a schematic block diagram of another method for detecting cable insulation resistance according to an embodiment of the present application;

图7是本申请实施例提供的一种针对交流线缆对地低绝缘阻抗检测方法的示意框图；FIG. 7 is a schematic block diagram of a method for detecting low insulation resistance of an AC cable to ground according to an embodiment of the present application;

图8是本申请实施例提供的一种针对交流线缆相间阻抗低且对地高绝缘阻抗检测方法的示意图；FIG. 8 is a schematic diagram of a method for detecting AC cables with low phase-to-phase impedance and high insulation impedance to ground according to an embodiment of the present application;

图9是本申请实施例提供的一种线缆绝缘阻抗检测装置的示意性框图；FIG. 9 is a schematic block diagram of a cable insulation resistance detection device provided by an embodiment of the present application;

图10是本申请实施例提供的另一种线缆绝缘阻抗检测装置的示意性框图。FIG. 10 is a schematic block diagram of another cable insulation resistance detection device provided by an embodiment of the present application.

具体实施方式Detailed ways

下面将结合附图，对本申请中的技术方案进行描述。The technical solution in this application will be described below in conjunction with the accompanying drawings.

图1是集中式架构的示意性结构图，用于光伏发电站中进能量的转换。集中式架构一般采用DC-AC一级转换电路对直流电进行转换。Figure 1 is a schematic structural diagram of a centralized architecture, used for the conversion of incoming energy in a photovoltaic power station. The centralized architecture generally uses a DC-AC primary conversion circuit to convert the direct current.

光伏组件也可以称为光伏阵列，包括多个光伏组串。每个光伏组串包括多个串联的光伏板。光伏板用于将光能转化为电能。光伏板产生的电能为直流(direct current，DC)电。光伏组串两端的电压等于该多个光伏板产生的电压之和。Photovoltaic modules can also be called photovoltaic arrays, including multiple photovoltaic strings. Each photovoltaic string includes a plurality of photovoltaic panels connected in series. Photovoltaic panels are used to convert light energy into electrical energy. The electricity generated by photovoltaic panels is direct current (DC) electricity. The voltage across the photovoltaic string is equal to the sum of the voltages generated by the multiple photovoltaic panels.

汇流箱用于将该多个光伏组串产生的电能进行汇流(一般有8路、12路或者16路等)，并将汇流后的输出经过断路开关和防雷处理后，输入逆变器，进行集中逆变和并网。应当理解，集中式架构的汇流箱对输入的电能不进行转换。The combiner box is used to converge the electric energy generated by the multiple photovoltaic strings (usually 8, 12, or 16, etc.), and the converged output is input into the inverter after being subjected to a circuit breaker and lightning protection treatment. Carry out centralized inverter and grid connection. It should be understood that the centralized structure of the combiner box does not convert the input electrical energy.

逆变器用于，将输入的直流电转换为交流(alternating current，AC)电，即进行DC-AC转换。The inverter is used to convert the input DC power into alternating current (AC) power, that is, to perform DC-AC conversion.

变压器可以用于对交流电进行转换，调整交流电压的电压值，输出交流电。应当理解，变压器可以对多个逆变器输出的交流电的进行升压。变压器的输出可以与电网连接。一般情况下，变压器仅对一个交流输入进行电压转换。当变压器设置有双***绕组时，变压器可以对两个交流输入进行电压转换。The transformer can be used to convert alternating current, adjust the voltage value of the alternating voltage, and output alternating current. It should be understood that the transformer can boost the AC power output by multiple inverters. The output of the transformer can be connected to the grid. Generally, the transformer only performs voltage conversion on one AC input. When the transformer is provided with double split windings, the transformer can perform voltage conversion on two AC inputs.

应理解，图1所示的集中式架构只是本申请实施例的方法应用的一种可能的架构，并不构成对本申请实施例限定，除了图1所示的集中式结构，本申请实施例的方法还可以应用于集散式架构或组串式架构等其他光伏发电站架构。It should be understood that the centralized architecture shown in FIG. 1 is only a possible architecture for the application of the method in the embodiment of the present application, and does not constitute a limitation to the embodiment of the present application. In addition to the centralized structure shown in FIG. The method can also be applied to other photovoltaic power station architectures such as distributed architecture or string architecture.

目前大型光伏电站一般通过光伏组件串联接入逆变器。多个逆变器的输出端通过线缆接到箱变低压柜中的MCCB断路器里面，MCCB断路器通过框架断路器连接至升压变压器，并35kV中断电网。逆变器输出端线缆通常是地沟的布线方式，在布线过程中容易出现线缆破皮，相间短路或者对地阻抗异常，导致交流侧电合MCCB断路器时，大的短路电流易导致MCCB开关喷弧，甚至烧毁，需要现场检修。一般可能出现的问题包括：线缆破皮，对地为低阻抗状态；线缆破皮，对地为高阻抗状态。At present, large-scale photovoltaic power plants generally connect inverters in series through photovoltaic modules. The output terminals of multiple inverters are connected to the MCCB circuit breaker in the low-voltage cabinet of the substation through cables. The MCCB circuit breaker is connected to the step-up transformer through the frame circuit breaker, and the 35kV interrupts the power grid. The cable at the output end of the inverter is usually wired in a trench. During the wiring process, the cable is prone to breakage, short circuit between phases or abnormal impedance to the ground. When the MCCB circuit breaker is closed on the AC side, a large short-circuit current can easily lead to MCCB. The switch sprays arc, or even burns, and needs on-site inspection and repair. Common problems that may occur include: the cable is broken, and the ground is in a low impedance state; the cable is broken, and the ground is in a high impedance state.

目前对交流线缆绝缘阻抗的检测一般为摇表检测方式。图2示出了交流线缆绝缘阻抗摇表检测示意图。在施工人员布好线缆之后，专业技术人员采用摇表的方式对交流侧线缆进行绝缘阻抗测试。针对线缆破皮，对地为低阻抗状态，通过摇表单根线缆逐步测量，判断其对地阻抗是否异常。针对线缆破皮，对地为高阻抗状态但相间阻抗低的情况，通常采用将其中两相线缆接地，用摇表测试另外一相线缆对地阻抗，例如将图2中的A相线缆和B相线缆接地，用摇表测试C相线缆的对地阻抗，从而判断C相线缆相对A、B相线缆的绝缘阻抗是否正常。At present, the insulation resistance of AC cables is generally tested by shaking meters. Figure 2 shows a schematic diagram of AC cable insulation resistance testing. After the construction personnel have laid out the cables, the professional technicians use the meter to test the insulation resistance of the AC side cables. In view of the broken skin of the cable and the low impedance to the ground, it is determined whether the impedance to the ground is abnormal by gradually measuring the root cable by shaking it. For the case where the cable is broken and the ground is in a high impedance state but the impedance between phases is low, usually two phases of the cable are grounded, and the other phase of the cable is tested with a shaker to the ground impedance, for example, the phase A in Figure 2 The cable and the B-phase cable are grounded. Use a shake meter to test the ground impedance of the C-phase cable to determine whether the insulation impedance of the C-phase cable relative to the A and B-phase cables is normal.

由于技术人员摇表检测交流线缆绝缘阻抗安全性低且线缆施工检测成本高，因此本申请实施例提供一种线缆绝缘检测方法，可以利用逆变器自动检测出施工导致的交流线缆绝缘阻抗低的问题，从而提高检测安全性，降低检测成本。Since technicians shake the meter to detect AC cable insulation impedance, the safety is low and the cable construction detection cost is high. Therefore, the embodiment of the present application provides a cable insulation detection method, which can automatically detect the AC cable caused by construction by using an inverter. The problem of low insulation resistance, thereby improving detection safety and reducing detection costs.

图3示出了本申请实施例提供的一种线缆绝缘阻抗检测方法的流程图，如图3所示，该方法包括步骤301至303，图4是图3方法的示意性框图，以下结合图4对图3的步骤分别介绍。FIG. 3 shows a flowchart of a method for detecting cable insulation resistance according to an embodiment of the present application. As shown in FIG. 3, the method includes steps 301 to 303. FIG. 4 is a schematic block diagram of the method in FIG. Figure 4 introduces the steps of Figure 3 respectively.

S301，将多条交流线缆中的待测交流线缆与逆变器的直流母线断开，并执行直流侧对地绝缘阻抗检测程序，以检测得到第一阻抗Riso1。S301: Disconnect the AC cable to be tested among the multiple AC cables from the DC bus of the inverter, and execute the DC side-to-ground insulation impedance detection program to detect the first impedance Riso1.

具体地，结合图4，在直流侧有电且并网继电器全都不吸合的情况下，逆变器执行直流侧对地绝缘阻抗检测。此时检测得到的直流侧对地阻抗为R1//R2，记为Riso1，其中//表示阻抗运算并联。应理解，直流侧对地绝缘检测功能时逆变器行业IEC62109-2强制功能，逆变器都具备该功能。Specifically, with reference to FIG. 4, in the case where there is power on the DC side and none of the grid-connected relays are turned on, the inverter performs the DC side insulation impedance detection to the ground. At this time, the measured impedance of the DC side to ground is R1//R2, denoted as Riso1, where // indicates that the impedance calculation is connected in parallel. It should be understood that the inverter industry IEC62109-2 compulsory function for the DC side insulation detection function to the ground, and the inverter has this function.

S302，将待测交流线缆与直流母线的正极或负极电连通，并执行直流侧对地绝缘阻抗检测程序，以检测得到第二阻抗Riso2。S302: Connect the AC cable to be tested with the positive electrode or the negative electrode of the DC bus, and execute the DC side insulation impedance detection program to ground to detect the second impedance Riso2.

具体地，结合图4，可以控制逆变器电连接的三条线缆中的任意一相线缆所对应的继电器吸合，例如记为A相。然后控制A相对应的直流母线正极侧的开关管按照一定脉宽导通，使得A相的输出线缆与直流母线的正极相连；或者控制A相对应的直流母线负极侧的开关管按照一定脉宽导通，使得A相的输出线缆与直流母线的负极相连。这里的一定脉宽可以是人为设定的，本申请实施例在此不做限定。接着逆变器执行直流侧对地绝缘阻抗检测，此时检测得到的直流侧对地阻抗为R1//R2//R3，记为Riso2，其中R3为A相线缆的对地绝缘阻抗。Specifically, in conjunction with FIG. 4, the relay corresponding to any one of the three cables electrically connected to the inverter can be controlled to pull in, for example, it is marked as A phase. Then control the switch tube on the positive side of the DC bus corresponding to A to conduct according to a certain pulse width, so that the output cable of phase A is connected to the positive side of the DC bus; or control the switch tube on the negative side of the DC bus corresponding to A according to a certain pulse The wide conduction makes the A-phase output cable connect to the negative pole of the DC bus. The certain pulse width here can be artificially set, which is not limited in the embodiment of the present application. Then the inverter performs DC side-to-ground insulation impedance detection. At this time, the detected DC side-to-ground impedance is R1//R2//R3, which is denoted as Riso2, where R3 is the insulation resistance of the A-phase cable to ground.

可选地，可以控制逆变器电连接的三条线缆中的任意两相线缆所对应的继电器吸合，例如记为A相和B相。然后与上述类似，控制A相、B相对应的直流母线正极侧的开关管或直流母线负极侧的开关管按照一定脉宽导通，使得A相的输出线缆与直流母线的正极相连或使得A相的输出线缆与直流母线的负极相连，使得B相的输出线缆与直流母线的正极相连或使得B相的输出线缆与直流母线的负极相连。即有四种可能：A正B正、A负B负、A正B负、A负B正，其中“A正”表示A相的输出线缆与直流母线的正极相连，以此类推。接着逆变器执行直流侧对地绝缘阻抗检测，此时检测得到的直流侧对地阻抗为R1//R2//R3//R4，记为Riso2，其中R3//R4为A相和B相线缆的对地总绝缘阻抗。Optionally, the relay corresponding to any two-phase cable among the three cables electrically connected to the inverter can be controlled to pull in, for example, it is denoted as A-phase and B-phase. Then similar to the above, control the switch tube on the positive side of the DC bus corresponding to phase A and B or the switch tube on the negative side of the DC bus to conduct according to a certain pulse width, so that the output cable of phase A is connected to the positive side of the DC bus or makes The A-phase output cable is connected to the negative pole of the DC bus, so that the B-phase output cable is connected to the positive pole of the DC bus or the B-phase output cable is connected to the negative pole of the DC bus. That is, there are four possibilities: A positive B positive, A negative B negative, A positive B negative, A negative B positive, where "A positive" means that the output cable of phase A is connected to the positive pole of the DC bus, and so on. Then the inverter performs the DC side-to-earth insulation impedance test. At this time, the detected DC side-to-earth impedance is R1//R2//R3//R4, which is denoted as Riso2, where R3//R4 is phase A and phase B The total insulation resistance of the cable to the ground.

可选地，可以控制逆变器电连接的三条线缆所对应的继电器全部吸合，例如记为A相、B相和C相。然后与上述类似，控制A相、B相和C相对应的直流母线正极侧的开关管或直流母线负极侧的开关管按照一定脉宽导通，使得A相的输出线缆与直流母线的正极相连或使得A相的输出线缆与直流母线的负极相连，使得B相的输出线缆与直流母线的正极相连或使得B相的输出线缆与直流母线的负极相连，使得C相的输出线缆与直流母线的正极相连或使得C相的输出线缆与直流母线的负极相连。即有八种可能：A正B正C正、A正B正C负、A负B正C正、A正B负C正、A正B负C负、A负B正C负、A负B负C正、A负B负C负，其中“A正”表示A相的输出线缆与直流母线的正极相连，以此类推。接着逆变器执行直流侧对地绝缘阻抗检测，此时检测得到的直流侧对地阻抗为R1//R2//R3//R4//R5，记为Riso2，其中R3//R4//R5为A相、B相和C相线缆的对地总绝缘阻抗。Optionally, it is possible to control all the relays corresponding to the three cables electrically connected to the inverter to pull in, for example, denoted as A-phase, B-phase, and C-phase. Then, similar to the above, control the switch tube on the positive side of the DC bus corresponding to phase A, B and C or the switch tube on the negative side of the DC bus to conduct according to a certain pulse width, so that the output cable of phase A is connected to the positive side of the DC bus. Connect or connect the output cable of phase A to the negative pole of the DC bus, connect the output cable of phase B to the positive pole of the DC bus, or connect the output cable of phase B to the negative pole of the DC bus, so that the output cable of phase C is connected The cable is connected to the positive pole of the DC bus or the C-phase output cable is connected to the negative pole of the DC bus. That is, there are eight possibilities: A positive, B positive, C positive, A positive, B positive, C negative, A negative, B positive, C positive, A positive, B negative, C positive, A positive, B negative, C negative, A negative, B positive, C negative, A negative B negative C positive, A negative B negative C negative, where "A positive" means that the output cable of phase A is connected to the positive pole of the DC bus, and so on. Then the inverter performs the DC side-to-earth insulation impedance test. At this time, the detected DC side-to-earth impedance is R1//R2//R3//R4//R5, which is marked as Riso2, where R3//R4//R5 It is the total insulation resistance to ground of the A-phase, B-phase and C-phase cables.

S303，根据Riso1和Riso2，确定待测交流线缆的对地绝缘阻抗。S303: Determine the insulation resistance to ground of the AC cable to be tested according to Riso1 and Riso2.

结合图4，具体地，当只测逆变器电连接的三条线缆中的任意一相线缆的对地绝缘阻抗，例如A相线缆的对地绝缘阻抗R3，则计算出R3＝Riso1ⅹRiso2/(Riso1-Riso2)。With reference to Figure 4, specifically, when only measuring the insulation resistance to ground of any one phase cable of the three cables electrically connected to the inverter, for example, the insulation resistance to ground R3 of the phase A cable, then R3=Riso1ⅹRiso2 is calculated /(Riso1-Riso2).

可选地，当测逆变器电连接的三条线缆中的任意两相线缆的对地总绝缘阻抗，例如A相、B相线缆的对地总绝缘阻抗R3//R4，则计算出R3//R4＝Riso1ⅹRiso2/(Riso1-Riso2)。Optionally, when measuring the total insulation resistance to ground of any two-phase cable among the three cables electrically connected to the inverter, for example, the total insulation resistance to ground R3//R4 of the A-phase and B-phase cables, then calculate R3//R4=Riso1ⅹRiso2/(Riso1-Riso2).

可选地，当测逆变器电连接的三条线缆的对地总绝缘阻抗，例如A相、B相、C相线缆的对地总绝缘阻抗R3//R4//R5，则计算出R3//R4//R5＝Riso1ⅹRiso2/(Riso1-Riso2)。Optionally, when measuring the total insulation resistance to ground of the three cables electrically connected to the inverter, for example, the total insulation resistance to ground R3//R4//R5 of the A-phase, B-phase, and C-phase cables, then calculate R3//R4//R5=Riso1ⅹRiso2/(Riso1-Riso2).

应理解，除了上述举例介绍，根据S301至S303的步骤还可以计算逆变器电连接的任意多条线缆的对地总绝缘阻抗，为了简洁，本申请实施例在此不作赘述。It should be understood that, in addition to the above examples, the total insulation resistance to ground of any number of cables electrically connected to the inverter can also be calculated according to the steps S301 to S303. For brevity, the embodiments of the present application will not repeat them here.

可选地，在检测得到Riso1之后，还可以判断Riso1是否大于第一阈值。若Riso1小于第一阈值，则停止检测，生成告警信息；若Riso1大于或等于第一阈值，则继续S302和S303的步骤。其中第一阈值可以是人为规定的值，本申请实施例在此不做限定。Optionally, after Riso1 is detected, it can also be determined whether Riso1 is greater than the first threshold. If Riso1 is less than the first threshold, stop detection and generate alarm information; if Riso1 is greater than or equal to the first threshold, continue with the steps of S302 and S303. The first threshold may be a value that is artificially specified, which is not limited in the embodiment of the present application.

在计算出待测交流线缆的对地绝缘阻抗(例如上述举例中的R3或R3//R4或R3//R4//R5)之后，本申请实施例的方法还包括，判断该待测交流线缆的对地绝缘阻抗是否大于第二阈值。若待测交流线缆的对地绝缘阻抗值小于第二阈值，则生成告警信息；若待测交流线缆对地绝缘阻抗值大于或等于第二阈值，则生成表示该待测交流线缆对地绝缘阻抗值正常的信息。其中第二阈值可以是人为规定的值，本申请实施例在此不做限定。After calculating the ground insulation impedance of the AC cable to be tested (for example, R3 or R3//R4 or R3//R4//R5 in the above example), the method of the embodiment of the present application further includes determining the AC cable to be tested Whether the cable's insulation resistance to ground is greater than the second threshold. If the insulation resistance to ground of the AC cable to be tested is less than the second threshold, an alarm message is generated; if the insulation resistance to ground of the AC cable to be tested is greater than or equal to the second threshold, it is generated to indicate that the AC cable Information indicating that the ground insulation resistance value is normal. The second threshold may be a value that is artificially specified, which is not limited in the embodiment of the present application.

图5示出了本申请实施例提供的另一种线缆绝缘阻抗检测方法的流程图，如图5所示，该方法包括步骤501至504，图6是图5方法的示意性框图，以下结合图6对图5的步骤分别介绍。FIG. 5 shows a flowchart of another method for detecting cable insulation resistance provided by an embodiment of the present application. As shown in FIG. 5, the method includes steps 501 to 504. FIG. 6 is a schematic block diagram of the method in FIG. The steps of Fig. 5 are respectively introduced in conjunction with Fig. 6.

S501，导通两相交流线缆对应的并网开关，并对两相交流线缆中的第一相交流线缆对应的第一滤波电容充电。S501: Turn on the grid-connecting switch corresponding to the two-phase AC cable, and charge the first filter capacitor corresponding to the first-phase AC cable in the two-phase AC cable.

具体地，结合图6，将两相交流线缆记为A相和B相。控制A相和B相交流线缆对应的继电器闭合，然后控制其中一相例如A相线缆对应的直流母线间桥臂的开关管导通或断开，给A相线缆对应的第一滤波电容充电，可以将该第一滤波电容记为Ca，充电后的Ca成为A、B相线缆间的绝缘测试激励源。Specifically, referring to Fig. 6, the two-phase AC cables are denoted as A-phase and B-phase. Control the relays corresponding to the A-phase and B-phase AC cables to close, and then control one of the phases, such as the switch tube of the bridge arm between the DC bus corresponding to the A-phase cable to turn on or off, to give the first filter corresponding to the A-phase cable For capacitor charging, the first filter capacitor can be denoted as Ca, and the charged Ca becomes the excitation source for the insulation test between the A and B phase cables.

S502，以第一滤波电容作为激励源，对两相交流线缆中的第二相交流线缆对应的第二滤波电容充电。S502: Use the first filter capacitor as an excitation source to charge the second filter capacitor corresponding to the second-phase AC cable in the two-phase AC cable.

具体地，结合图6，通过A相和B相线缆对应的并网开关、A相和B相线缆对应的滤波电容、A相和B相线缆的对地绝缘阻抗R3和R4形成电流回路，Ca作为绝缘测试激励源给B相线缆对应的滤波电容Cb充电。Specifically, in conjunction with Figure 6, the current is formed by the grid-connected switches corresponding to the A-phase and B-phase cables, the filter capacitors corresponding to the A-phase and B-phase cables, and the ground insulation resistances R3 and R4 of the A-phase and B-phase cables. In the loop, Ca is used as an excitation source for insulation testing to charge the filter capacitor Cb corresponding to the B-phase cable.

S503，检测第一滤波电容和第二滤波电容上的电压。S503: Detect the voltage on the first filter capacitor and the second filter capacitor.

控制检测电路获取到A相和B相线缆对应的第一滤波电容Ca和第二滤波电容Cb上的电压Ua和Ub。The control detection circuit obtains the voltages Ua and Ub on the first filter capacitor Ca and the second filter capacitor Cb corresponding to the A-phase and B-phase cables.

S504，根据第一滤波电容和第二滤波电容上的电压，确定两相交流线缆之间的相间绝缘阻抗。S504: Determine the phase-to-phase insulation impedance between the two-phase AC cables according to the voltages on the first filter capacitor and the second filter capacitor.

具体地，A相和B相两相交流线缆之间的相间绝缘阻抗R3+R4＝-t/(Cbⅹln(1-Ub/Ua))。其中，t为对所述第二滤波电容充电的时间。Specifically, the phase-to-phase insulation resistance R3+R4=-t/(Cbⅹln(1-Ub/Ua)) between the A-phase and B-phase two-phase AC cables. Wherein, t is the time for charging the second filter capacitor.

可选地，还可以通过漏电流传感器检测电流回路中的电路I，从而A相和B相两相交流线缆之间的相间绝缘阻抗R3+R4＝(Ua+Ub)/I。Optionally, the circuit I in the current loop can also be detected by a leakage current sensor, so that the phase-to-phase insulation resistance R3+R4=(Ua+Ub)/I between the A-phase and B-phase two-phase AC cables.

可选地，在对两相交流线缆中的第一相交流线缆对应的第一滤波电容充电之前，本申请实施例的方法还包括，控制逆变器的直流母线的电压值大于或等于电网线电压不控整流值。例如，逆变器的直流母线的电压值为500V，电网线电压不控整流值为707V时，可以通过BST提高直流母线的电压值。这是由于在该步骤中如果误闭合MCCB，可能造成逆变器损坏，为规避风险，需要控制逆变器的直流母线的电压值大于或等于电网线电压不控整流值。Optionally, before charging the first filter capacitor corresponding to the first phase of the two-phase AC cable, the method of the embodiment of the present application further includes controlling the voltage value of the DC bus of the inverter to be greater than or equal to The grid line voltage does not control the rectification value. For example, when the voltage value of the DC bus of the inverter is 500V, and the uncontrolled rectification value of the grid line voltage is 707V, BST can be used to increase the voltage of the DC bus. This is because if the MCCB is closed by mistake in this step, the inverter may be damaged. In order to avoid the risk, the voltage value of the DC bus of the inverter needs to be controlled to be greater than or equal to the uncontrolled rectification value of the grid line voltage.

在计算出两相交流线缆之间的相间绝缘阻抗(例如上述举例中的R3+R4)之后，本申请实施例的方法还包括，判断该两相交流线缆之间的相间绝缘阻抗是否大于第三阈值。若两相交流线缆之间的相间绝缘阻抗小于第三阈值，则生成告警信息；若两相交流线缆之间的相间绝缘阻抗大于或等于第三阈值，则生成表示该两相交流线缆之间的相间绝缘阻抗正常的信息。其中第三阈值可以是人为规定的值，本申请实施例在此不做限定。After calculating the phase-to-phase insulation resistance between the two-phase AC cables (for example, R3+R4 in the above example), the method of the embodiment of the present application further includes determining whether the phase-to-phase insulation resistance between the two-phase AC cables is greater than The third threshold. If the phase-to-phase insulation resistance between two-phase AC cables is less than the third threshold, an alarm message is generated; if the phase-to-phase insulation resistance between two-phase AC cables is greater than or equal to the third threshold, it is generated to indicate the two-phase AC cables Information that the insulation resistance between phases is normal. The third threshold may be a value artificially specified, which is not limited in the embodiment of the present application.

以下结合图7和图8分别对交流线缆对地低绝缘阻抗的检测方法和相间阻抗低且相对地高绝缘阻抗的检测方法作具体介绍。The following specifically introduces the detection method of the AC cable's low insulation resistance to the ground and the detection method of the phase-to-phase impedance and the relatively high insulation resistance to the ground in conjunction with FIG. 7 and FIG. 8.

图7是本申请实施例提供的一种针对交流线缆对地低绝缘阻抗检测方法的示意框图。如图7所示的逆变器，包括一个DC/DC变换单元，可选地，也可以包括多个DC/DC变换单元，电容C1和电容C2串联构成母线单元，C1和C2的连接点为母线中点O。其中DC/DC变换单元的输入端接光伏组件的输出端，DC/DC变换单元的输出端接直流母线的正、负端。逆变器中的DC/AC逆变单元由三个DC/AC变换电路构成，其中A相的DC/AC变换电路包括A-Q1、A-Q2、A-Q3、A-Q4组成的高频斩波电路、La滤波电感和Ca滤波电容。A相的DC/AC变换电路输出端连接并网开关单元K1开关，可选地，K1开关可以由多个快关串联构成，K1开关的输出端通过输出单元连接电网侧A相线缆。B相的DC/AC变换电路包括B-Q1、B-Q2、B-Q3、B-Q4组成的高频斩波电路、La滤波电感和Ca滤波电容。B相的DC/AC变换电路输出端连接并网开关单元K2开关，可选地，K2开关可以由多个快关串联构成，K2开关的输出端通过输出单元连接电网侧B相线缆。C相的DC/AC变换电路包括C-Q1、C-Q2、C-Q3、C-Q4组成的高频斩波电路、La滤波电感和Ca滤波电容。C相的DC/AC变换电路输出端连接并网开关单元K3开关，可选地，K3开关可以由多个快关串联构成，K3开关的输出端通过输出单元连接电网侧C相线缆。逆变器中控制单元包含逆变器直流侧对地绝缘阻抗检测程序，该程序满足IEC62109-2标准中的方阵绝缘阻抗检测的要求。图7中R1和R2为光伏子阵正负极对地的绝缘阻抗值，R3、R4、R5为逆变器输出交流线缆对地的绝缘阻抗值。FIG. 7 is a schematic block diagram of a method for detecting low insulation resistance of an AC cable to ground according to an embodiment of the present application. The inverter as shown in Figure 7 includes a DC/DC conversion unit. Optionally, it may also include multiple DC/DC conversion units. A capacitor C1 and a capacitor C2 are connected in series to form a bus unit. The connection point of C1 and C2 is The midpoint of the bus is O. The input end of the DC/DC conversion unit is connected to the output end of the photovoltaic module, and the output end of the DC/DC conversion unit is connected to the positive and negative ends of the DC bus. The DC/AC inverter unit in the inverter is composed of three DC/AC conversion circuits, and the A-phase DC/AC conversion circuit includes high-frequency components composed of A-Q1, A-Q2, A-Q3, and A-Q4. Chopper circuit, La filter inductor and Ca filter capacitor. The output end of the A-phase DC/AC conversion circuit is connected to the grid-connected switch unit K1 switch. Optionally, the K1 switch can be composed of multiple quick switches in series, and the output end of the K1 switch is connected to the grid-side A-phase cable through the output unit. The B-phase DC/AC conversion circuit includes a high-frequency chopper circuit composed of B-Q1, B-Q2, B-Q3, and B-Q4, La filter inductor and Ca filter capacitor. The output terminal of the B-phase DC/AC conversion circuit is connected to the grid-connected switch unit K2 switch. Optionally, the K2 switch may be composed of a plurality of quick switches in series, and the output terminal of the K2 switch is connected to the grid-side B-phase cable through the output unit. The C-phase DC/AC conversion circuit includes a high-frequency chopper circuit composed of C-Q1, C-Q2, C-Q3, and C-Q4, La filter inductor and Ca filter capacitor. The output terminal of the C-phase DC/AC conversion circuit is connected to the grid-connected switch unit K3 switch. Optionally, the K3 switch can be composed of a plurality of quick switches in series, and the output terminal of the K3 switch is connected to the grid-side C-phase cable through the output unit. The control unit in the inverter includes a test program for the insulation resistance of the inverter's DC side to ground, which meets the requirements of the square matrix insulation resistance test in the IEC62109-2 standard. In Figure 7, R1 and R2 are the insulation resistance values of the positive and negative poles of the photovoltaic sub-array to the ground, and R3, R4, and R5 are the insulation resistance values of the inverter output AC cables to the ground.

在逆变器有光伏电源输入、交流输出侧无电网电压的情况下，当交流线缆对地低绝缘阻抗时，检测逆变器输出端交流线缆对地绝缘阻抗值的步骤如下，以A相线缆为例：When the inverter has photovoltaic power input and no grid voltage on the AC output side, when the AC cable has low insulation resistance to the ground, the steps to detect the insulation resistance of the AC cable to the ground at the output of the inverter are as follows: Take the phase cable as an example:

1、在直流侧有电并网开关单元不吸合的情况下，执行直流侧对地绝缘阻抗检测程序，先检测出直流侧对地阻抗Riso1＝R1//R2。1. When the grid-connected switch unit on the DC side does not pull in, execute the DC side-to-ground insulation impedance detection program, and first detect the DC side-to-ground impedance Riso1=R1//R2.

2、控制单元只控制A相K1开关吸合，并将逆变器A相A-Q1管按照一定脉宽控制将其导通，使得A相交流输出线缆与母线单元正极相连；或者将逆变器A相A-Q4管按照一定脉宽控制将其导通，使得A相的交流输出线缆与母线单元负极相连。2. The control unit only controls the A-phase K1 switch to pull in, and the inverter A-phase A-Q1 tube is turned on according to a certain pulse width control, so that the A-phase AC output cable is connected to the positive pole of the bus unit; or the reverse The A-Q4 tube of phase A of the converter turns it on according to a certain pulse width control, so that the AC output cable of phase A is connected to the negative pole of the bus unit.

3、控制单元执行直流侧对地绝缘阻抗检测程序，检测到的值为直流侧阻抗并A相线缆对地绝缘阻抗Riso2，又由于Riso2＝R1//R2//R3，因此通过换算可以得到A相对地绝缘阻抗值R3＝Riso1ⅹRiso2/(Riso1-Riso2)。3. The control unit executes the DC side-to-ground insulation impedance detection program, the detected value is the DC side impedance and the A-phase cable-to-ground insulation resistance Riso2, and because Riso2=R1//R2//R3, it can be obtained by conversion A relative to ground insulation resistance value R3=Riso1ⅹRiso2/(Riso1-Riso2).

4、检测完毕后，先关闭A-Q1管(或A-Q4管)，再断开K1开关。4. After the detection is completed, first turn off the A-Q1 tube (or A-Q4 tube), and then turn off the K1 switch.

5、同理，按照1-4的步骤可以检测并计算出B相对地绝缘阻抗值R4以及C相对地绝缘阻抗值R5。5. In the same way, follow the steps 1-4 to detect and calculate the B-to-ground insulation resistance value R4 and C-to-ground insulation resistance value R5.

根据本申请实施例提供的针对交流线缆对地低绝缘阻抗检测方法，也可以同时检测任两相总对地绝缘阻抗值，以同时检测A相和B相对地绝缘总阻抗值为例，检测步骤如下：According to the method for detecting low insulation resistance of AC cables to ground provided by the embodiments of the present application, the total insulation resistance to ground of any two phases can also be detected at the same time. Proceed as follows:

2、控制单元控制A相K1开关和B相K2开关吸合，或者控制单元控制母线电压大于或等于电网线电压不控整流电压值后，再控制A相K1开关和B相K2开关吸合。这是由于在该步骤中，如果误闭合MCCB，会造成逆变器和MCCB损坏的风险，为了规避风险，需要在母线电压大于电网不控整流电压时才能进行该步骤。然后将逆变器A相A-Q1管按照一定脉宽控制将其导通，使的A相交流输出线缆和母线正极相连，或者将逆变器A相A-Q4管按照一定脉宽控制将其导通，使的A相交流输出线缆和母线负极相连。同时逆变器B相B-Q1管按照一定脉宽控制将其导通，使的B相交流输出线缆和母线正极相连，或者将逆变器B相B-Q4管按照一定脉宽控制将其导通，使的B相交流输出线缆和母线负极相连。2. The control unit controls the A-phase K1 switch and the B-phase K2 switch to pull in, or the control unit controls the bus voltage to be greater than or equal to the uncontrolled rectified voltage of the grid line voltage, and then controls the A-phase K1 switch and the B-phase K2 switch to pull in. This is because in this step, if the MCCB is closed by mistake, it will cause the risk of damage to the inverter and MCCB. In order to avoid the risk, it is necessary to perform this step when the bus voltage is greater than the uncontrolled rectified voltage of the grid. Then turn on the inverter A-phase A-Q1 tube according to a certain pulse width control, and connect the A-phase AC output cable to the positive bus bar, or control the inverter A-phase A-Q4 tube according to a certain pulse width Turn it on to connect the A-phase AC output cable to the negative pole of the bus. At the same time, the inverter B-phase B-Q1 tube is turned on according to a certain pulse width control, so that the B-phase AC output cable is connected to the positive bus bar, or the inverter B-phase B-Q4 tube is controlled according to a certain pulse width. Its conduction connects the B-phase AC output cable to the negative pole of the bus.

3、控制单元再执行直流侧对地绝缘阻抗检测程序，检测出的值为直流侧阻抗并A、B两相线缆对地绝缘阻抗Riso2，其中又由于Riso2＝R1//R2//R3//R4，通过换算出，A、B两相对地总阻抗值R3//R4＝Riso1ⅹRiso2/(Riso1-Riso2)。3. The control unit then executes the DC side-to-ground insulation impedance detection program, and the detected value is the DC side impedance and the A and B two-phase cable-to-ground insulation resistance Riso2, where Riso2 = R1//R2//R3/ /R4, calculated by conversion, the total impedance value of A and B relative to the ground is R3//R4=Riso1ⅹRiso2/(Riso1-Riso2).

4，检测完后，关A-Q1(或A-Q4)、B-Q1(或B-Q4)管，再断开K1、K2开关。4. After testing, turn off the A-Q1 (or A-Q4) and B-Q1 (or B-Q4) tubes, and then disconnect the K1 and K2 switches.

5，同理按照1-4步骤分别检测并计算出B、C两相对地绝缘阻抗R4//R5和C、A两相对地绝缘阻抗值R3//R5。5. Similarly, according to steps 1-4, respectively detect and calculate the insulation resistance R4//R5 of B and C relative to the ground and the insulation resistance R3//R5 of C and A relative to the ground.

根据本申请实施例提供的针对交流线缆对地低绝缘阻抗检测方法，还可以同时检测三相总对地绝缘阻抗值，即A、B、C相总对地绝缘阻抗值R3//R4//R5。According to the method for detecting low insulation resistance of AC cables to ground provided by the embodiments of the present application, the total insulation resistance of three phases to ground can also be detected at the same time, that is, the total insulation resistance of phases A, B, and C is R3//R4/ /R5.

其中步骤1与上述相同。步骤2中，控制单元控制A相K1开关、B相K2开关和C相K3开关吸合，或者控制单元控制母线电压大于或等于电网线电压不控整流电压值后，再控制A相K1开关、B相K2开关和C相K3开关吸合。然后将逆变器A相A-Q1管按照一定脉宽控制将其导通，使的A相交流输出线缆和母线正极相连，或者将逆变器A相A-Q4管按照一定脉宽控制将其导通，使的A相交流输出线缆和母线负极相连。同时逆变器B相B-Q1管按照一定脉宽控制将其导通，使的B相交流输出线缆和母线正极相连，或者将逆变器B相B-Q4管按照一定脉宽控制将其导通，使的B相交流输出线缆和母线负极相连。逆变器C相C-Q1管按照一定脉宽控制将其导通，使的C相交流输出线缆和母线正极相连，或者将逆变器C相C-Q4管按照一定脉宽控制将其导通，使的C相交流输出线缆和母线负极相连。步骤3中，控制单元检测出的值为直流侧阻抗并A、B、C三相线缆对地绝缘阻抗Riso2，其中又由于Riso2＝R1//R2//R3//R4//R5，通过换算出，A、B、C三相对地总阻抗值R3//R4//R5＝Riso1ⅹRiso2/(Riso1-Riso2)。步骤4中，检测完毕后先关A-Q1(或A-Q4)、B-Q1(或B-Q4)、C-Q1(或C-Q4)管，再断开K1、K2、K3开关。Step 1 is the same as above. In step 2, the control unit controls the A-phase K1 switch, the B-phase K2 switch, and the C-phase K3 switch to pull in, or the control unit controls the bus voltage to be greater than or equal to the uncontrolled rectified voltage value of the grid line voltage, and then controls the A-phase K1 switch, The B-phase K2 switch and the C-phase K3 switch are closed. Then turn on the inverter A-phase A-Q1 tube according to a certain pulse width control, and connect the A-phase AC output cable to the positive bus bar, or control the inverter A-phase A-Q4 tube according to a certain pulse width Turn it on to connect the A-phase AC output cable to the negative pole of the bus. At the same time, the inverter B-phase B-Q1 tube is turned on according to a certain pulse width control, so that the B-phase AC output cable is connected to the positive bus bar, or the inverter B-phase B-Q4 tube is controlled according to a certain pulse width. Its conduction connects the B-phase AC output cable to the negative pole of the bus. The inverter C-phase C-Q1 tube is turned on according to a certain pulse width control, so that the C-phase AC output cable is connected to the positive bus bar, or the inverter C-phase C-Q4 tube is controlled according to a certain pulse width. Turn on, so that the C-phase AC output cable is connected to the negative pole of the bus. In step 3, the value detected by the control unit is the DC side impedance and the A, B, and C three-phase cable-to-ground insulation impedance Riso2, where Riso2 = R1//R2//R3//R4//R5. Converted, the total impedance value of A, B, C three phases to ground is R3//R4//R5=Riso1ⅹRiso2/(Riso1-Riso2). In step 4, turn off the A-Q1 (or A-Q4), B-Q1 (or B-Q4), and C-Q1 (or C-Q4) tubes after the detection is completed, and then disconnect the K1, K2, and K3 switches.

图8示出了本申请实施例提供的一种针对交流线缆相间阻抗低且对地高绝缘阻抗检测方法的示意图。如图8所示的逆变器以及与光伏组件的连接与图7中相同，具体可参照上述对于图7的介绍，为了简洁，在此不再赘述。FIG. 8 shows a schematic diagram of a method for detecting AC cables with low phase-to-phase impedance and high insulation impedance to ground according to an embodiment of the present application. The inverter shown in FIG. 8 and the connection with the photovoltaic module are the same as those in FIG. 7. For details, please refer to the introduction of FIG.

在逆变器有光伏电源输入、交流输出侧无电网电压的情况下，当交流线缆相间阻抗低且对地高阻抗时，检测逆变器输出端线缆之间绝缘阻抗的步骤如下，以A、B相线缆之间的绝缘阻抗为例：When the inverter has photovoltaic power input and there is no grid voltage on the AC output side, when the phase-to-phase impedance of the AC cable is low and the impedance to the ground is high, the steps to detect the insulation resistance between the cables at the output end of the inverter are as follows: Take the insulation resistance between A and B phase cables as an example:

1、控制单元控制A相并网开关K1和B相并网开关K2导通，A相的DC/AC变换电路中按照一定控制逻辑控制A-Q1管，给对应的滤波电容Ca充电。或者控制单元控制母线电压大于或等于电网线电压不控整流电压值后，再控制单元控制A相并网开关K1和B相并网开关K2导通，A相的DC/AC变换电路中按照一定控制逻辑控制A-Q1管，给对应的滤波电容Ca充电。1. The control unit controls the phase A grid-connected switch K1 and the phase B grid-connected switch K2 to be turned on, and the A-Q1 tube is controlled according to a certain control logic in the A-phase DC/AC conversion circuit to charge the corresponding filter capacitor Ca. Or after the control unit controls the bus voltage to be greater than or equal to the uncontrolled rectification voltage of the grid line voltage, the control unit controls the phase A grid switch K1 and the B phase grid switch K2 to turn on, and the A phase DC/AC conversion circuit is in accordance with a certain The control logic controls the A-Q1 tube to charge the corresponding filter capacitor Ca.

2、此时，滤波电容Ca形成了阻抗测试激励源，通过并网开关单元K1、输出单元、R3、R4、输出单元、并网开关单元K2、滤波电容Cb，形成电流路径，给Cb电容充电，等效为RC充电模型。控制单元通过检测电路获取到A、B两相滤波电容Ca、Cb上的电压Ua、Ub，计算出输出线缆之间的绝缘阻抗值R3+R4＝＝-t/(Cbⅹln(1-Ub/Ua))，其中t为Cb电容充电的时间。或者控制单元通过检测电路获取到两组DC/AC变换电路滤波电容Ca和Cb上的电压和漏电流传感器的检测的电流I，根据R＝U/I可以计算出输出线缆之间的绝缘阻抗值R3和R4。2. At this time, the filter capacitor Ca forms an impedance test excitation source, which forms a current path through the grid-connected switch unit K1, output unit, R3, R4, output unit, grid-connected switch unit K2, and filter capacitor Cb to charge the Cb capacitor , Equivalent to RC charging model. The control unit obtains the voltage Ua, Ub on the A and B two-phase filter capacitors Ca and Cb through the detection circuit, and calculates the insulation resistance value R3+R4==-t/(Cbⅹln(1-Ub/ Ua)), where t is the time to charge the Cb capacitor. Or the control unit obtains the voltage on the two sets of DC/AC conversion circuit filter capacitors Ca and Cb and the current I detected by the leakage current sensor through the detection circuit, and can calculate the insulation resistance between the output cables according to R=U/I Values R3 and R4.

3、检测完毕后，先关闭A-Q1管，再断开K1、K2开关。3. After the test is completed, first turn off the A-Q1 tube, and then turn off the K1 and K2 switches.

4、同理，按照1-3的步骤可以分别检测并计算出B相、C相线缆之间的绝缘阻抗值R4+R5，以及A相、C相之间的绝缘阻抗值R3+R5。4. In the same way, according to the steps 1-3, the insulation resistance value R4+R5 between the B-phase and C-phase cables and the insulation resistance value R3+R5 between the A-phase and C-phase can be detected and calculated respectively.

图9是本申请实施例提供的一种线缆绝缘阻抗检测装置的示意性框图，图9所示的装置900包括控制器910和检测电路920。FIG. 9 is a schematic block diagram of a cable insulation resistance detection device provided by an embodiment of the present application. The device 900 shown in FIG. 9 includes a controller 910 and a detection circuit 920.

控制器910，用于控制多条交流线缆中的待测交流线缆与逆变器的直流母线断开，并执行直流侧对地绝缘阻抗检测程序，根据检测电路920检测结果计算得到第一阻抗Riso1。The controller 910 is used to control the AC cable to be tested among the multiple AC cables to disconnect from the DC bus of the inverter, and execute the DC side-to-ground insulation impedance detection program, and calculate the first Impedance Riso1.

控制器910，还用于控制待测交流线缆与直流母线的正极或负极电连通，并执行直流侧对地绝缘阻抗检测程序，根据检测电路920检测结果计算得到第二阻抗Riso2。The controller 910 is also used to control the AC cable to be tested to be electrically connected to the positive or negative pole of the DC bus, and execute the DC side insulation impedance detection program to ground, and calculate the second impedance Riso2 according to the detection result of the detection circuit 920.

控制器910还用于根据Riso1和Riso2，确定待测交流线缆的对地绝缘阻抗。The controller 910 is also used to determine the insulation resistance to ground of the AC cable to be tested according to Riso1 and Riso2.

应理解，图9所示的装置900能够实现图3中的方法的各个步骤，具体可参照以上对于图3的方法的描述，为了简洁，本申请实施例不再赘述。It should be understood that the device 900 shown in FIG. 9 can implement each step of the method in FIG. 3. For details, reference may be made to the above description of the method in FIG.

可选地，控制器910可根据公式Riso1ⅹRiso2/(Riso1-Riso2)计算待测交流线缆的对地绝缘阻抗。Optionally, the controller 910 may calculate the insulation resistance to ground of the AC cable to be tested according to the formula Riso1ⅹRiso2/(Riso1-Riso2).

可选地，在控制器910根据检测电路920检测结果计算得到第一阻抗Riso1之后，控制器910还可以判断Riso1是否大于第一阈值。若Riso1小于第一阈值，则控制器910停止检测，生成告警信息；若Riso1大于或等于第一阈值，则控制器910继续检测。其中第一阈值可以是人为规定的值，本申请实施例在此不做限定。Optionally, after the controller 910 calculates the first impedance Riso1 according to the detection result of the detection circuit 920, the controller 910 may also determine whether Riso1 is greater than the first threshold. If Riso1 is less than the first threshold, the controller 910 stops the detection and generates alarm information; if Riso1 is greater than or equal to the first threshold, the controller 910 continues to detect. The first threshold may be a value that is artificially specified, which is not limited in the embodiment of the present application.

在控制器910计算出待测交流线缆的对地绝缘阻抗之后，控制器910还可以判断该待测交流线缆的对地绝缘阻抗是否大于第二阈值。若待测交流线缆的对地绝缘阻抗值小于第二阈值，则控制器910生成告警信息；若待测交流线缆对地绝缘阻抗值大于或等于第二阈值，则控制器910生成表示该待测交流线缆对地绝缘阻抗值正常的信息。其中第二阈值可以是人为规定的值，本申请实施例在此不做限定。After the controller 910 calculates the insulation resistance to ground of the AC cable to be tested, the controller 910 may also determine whether the insulation resistance to ground of the AC cable to be tested is greater than the second threshold. If the insulation resistance value to ground of the AC cable to be tested is less than the second threshold, the controller 910 generates alarm information; if the insulation resistance value to the ground of the AC cable to be tested is greater than or equal to the second threshold, the controller 910 generates Information indicating that the insulation resistance of the AC cable to be tested to the ground is normal. The second threshold may be a value that is artificially specified, which is not limited in the embodiment of the present application.

图10是本申请实施例提供的另一种线缆绝缘阻抗检测装置的示意性框图，图10所示的装置1000包括控制器1010和检测电路1020。FIG. 10 is a schematic block diagram of another cable insulation resistance detection device provided by an embodiment of the present application. The device 1000 shown in FIG. 10 includes a controller 1010 and a detection circuit 1020.

控制器1010，用于控制导通两相交流线缆对应的并网开关，并控制两相交流线缆中的第一相交流线缆对应的第一滤波电容充电。The controller 1010 is configured to control the grid-connecting switch corresponding to the two-phase AC cable and control the charging of the first filter capacitor corresponding to the first-phase AC cable in the two-phase AC cable.

控制器1010，还用于控制第一滤波电容作为激励源，对两相交流线缆中的第二相交流线缆对应的第二滤波电容充电。The controller 1010 is also used to control the first filter capacitor as an excitation source to charge the second filter capacitor corresponding to the second-phase AC cable in the two-phase AC cable.

检测电路1020，还用于检测第一滤波电容和第二滤波电容上的电压。The detection circuit 1020 is also used to detect the voltage on the first filter capacitor and the second filter capacitor.

控制器1010，用于根据第一滤波电容和第二滤波电容上的电压，确定两相交流线缆之间的相间绝缘阻抗。The controller 1010 is configured to determine the phase-to-phase insulation impedance between the two-phase AC cables according to the voltage on the first filter capacitor and the second filter capacitor.

应理解，图10所示的装置1000能够实现图5中的方法的各个步骤，具体可参照以上对于图5的方法的描述，为了简洁，本申请实施例不再赘述。It should be understood that the device 1000 shown in FIG. 10 can implement each step of the method in FIG. 5, and for details, refer to the above description of the method in FIG.

可选地，控制器1010可以根据公式-t/(Cbⅹln(1-Ub/Ua))计算两相交流线缆之间的相间绝缘阻抗，其中，t为对所述第二滤波电容充电的时间，Cb为所述第二滤波电容值，Ub为所述第二滤波电容上的电压，Ua为所述第一滤波电容上的电压。或者控制器1010可以根据公式(Ua+Ub)/I计算两相交流线缆之间的相间绝缘阻抗，其中I为通过漏电流传感器检测出的电流回路中的电流。Optionally, the controller 1010 can calculate the phase-to-phase insulation impedance between the two-phase AC cables according to the formula -t/(Cbⅹln(1-Ub/Ua)), where t is the time for charging the second filter capacitor , Cb is the second filter capacitor value, Ub is the voltage on the second filter capacitor, and Ua is the voltage on the first filter capacitor. Or the controller 1010 can calculate the phase-to-phase insulation resistance between the two-phase AC cables according to the formula (Ua+Ub)/I, where I is the current in the current loop detected by the leakage current sensor.

可选地，在控制器1010对两相交流线缆中的第一相交流线缆对应的第一滤波电容充电之前，控制器1010还可以控制逆变器的直流母线的电压值大于或等于电网线电压不控整流值。Optionally, before the controller 1010 charges the first filter capacitor corresponding to the first phase of the two-phase AC cables, the controller 1010 may also control the voltage value of the DC bus of the inverter to be greater than or equal to the grid The line voltage does not control the rectification value.

在控制器1010计算出两相交流线缆之间的相间绝缘阻抗之后，控制器1010还可以判断该两相交流线缆之间的相间绝缘阻抗是否大于第三阈值。若两相交流线缆之间的相间绝缘阻抗小于第三阈值，则控制器1010生成告警信息；若两相交流线缆之间的相间绝缘阻抗大于或等于第三阈值，则控制器1010生成表示该两相交流线缆之间的相间绝缘阻抗正常的信息。其中第三阈值可以是人为规定的值，本申请实施例在此不做限定。After the controller 1010 calculates the phase-to-phase insulation resistance between the two-phase AC cables, the controller 1010 can also determine whether the phase-to-phase insulation resistance between the two-phase AC cables is greater than the third threshold. If the phase-to-phase insulation resistance between the two-phase AC cables is less than the third threshold, the controller 1010 generates alarm information; if the phase-to-phase insulation resistance between the two-phase AC cables is greater than or equal to the third threshold, the controller 1010 generates Information indicating that the phase-to-phase insulation resistance between the two-phase AC cables is normal. The third threshold may be a value artificially specified, which is not limited in the embodiment of the present application.

应理解，图9和图10中的装置仅为便于理解而示例，控制器和检测电路也可以是其他等效的电路。基于相同的构思，本领域的技术人员可以在上述装置中作出等价变换，以达到实现相同或相似的效果。基于这些等价变换得到的线缆绝缘阻抗检测装置，依然能实现到本申请实施例的线缆绝缘阻抗检测方法。因此，这些等价变换均应落入本申请的保护范围。It should be understood that the devices in FIG. 9 and FIG. 10 are merely examples for ease of understanding, and the controller and the detection circuit may also be other equivalent circuits. Based on the same concept, those skilled in the art can make equivalent transformations in the above devices to achieve the same or similar effects. The cable insulation resistance detection device obtained based on these equivalent transformations can still achieve the cable insulation resistance detection method of the embodiment of the present application. Therefore, these equivalent transformations should fall into the protection scope of this application.

本申请实施例中，“至少一个”是指一个或者多个，“多个”是指两个或两个以上。“和/或”，描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示单独存在A、同时存在A和B、单独存在B的情况。其中A，B可以是单数或者复数。字符“/”一般表示前后关联对象是一种“或”的关系。“以下至少一项”及其类似表达，是指的这些项中的任意组合，包括单项或复数项的任意组合。例如，a，b和c中的至少一项可以表示：a,b,c,a-b,a-c,b-c,或a-b-c，其中a,b,c可以是单个，也可以是多个。所属领域的技术人员可以清楚地了解到，为描述的方便和简洁，上述描述的***、装置和单元的具体工作过程，可以参考前述方法实施例中的对应过程，在此不再赘述。In the embodiments of the present application, "at least one" refers to one or more, and "multiple" refers to two or more. "And/or" describes the association relationship of the associated objects, indicating that there can be three types of relationships, for example, A and/or B, which can mean that A exists alone, A and B exist at the same time, and B exists alone. Among them, A and B can be singular or plural. The character "/" generally indicates that the associated objects before and after are in an "or" relationship. "The following at least one item" and similar expressions refer to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b, and c can represent: a, b, c, a-b, a-c, b-c, or a-b-c, where a, b, and c can be single or multiple. Those skilled in the art can clearly understand that, for the convenience and conciseness of description, the specific working process of the system, device and unit described above can refer to the corresponding process in the foregoing method embodiment, which will not be repeated here.

本领域普通技术人员可以意识到，结合本文中所公开的实施例描述的各示例的单元及算法步骤，能够以电子硬件、或者计算机软件和电子硬件的结合来实现。这些功能究竟以硬件还是软件方式来执行，取决于技术方案的特定应用和设计约束条件。专业技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能，但是这种实现不应认为超出本申请的范围。A person of ordinary skill in the art may realize that the units and algorithm steps of the examples described in combination with the embodiments disclosed herein can be implemented by electronic hardware or a combination of computer software and electronic hardware. Whether these functions are executed by hardware or software depends on the specific application and design constraint conditions of the technical solution. Professionals and technicians can use different methods for each specific application to implement the described functions, but such implementation should not be considered beyond the scope of this application.

所属领域的技术人员可以清楚地了解到，为描述的方便和简洁，上述描述的***、装置和单元的具体工作过程，可以参考前述方法实施例中的对应过程，在此不再赘述。Those skilled in the art can clearly understand that, for the convenience and conciseness of description, the specific working process of the system, device and unit described above can refer to the corresponding process in the foregoing method embodiment, which will not be repeated here.

在本申请所提供的几个实施例中，应该理解到，所揭露的***、装置和方法，可以通过其它的方式实现。例如，以上所描述的装置实施例仅仅是示意性的，例如，所述单元的划分，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式，例如多个单元或组件可以结合或者可以集成到另一个***，或一些特征可以忽略，或不执行。另一点，所显示或讨论的相互之间的耦合或直接耦合或通信连接可以是通过一些接口，装置或单元的间接耦合或通信连接，可以是电性，机械或其它的形式。In the several embodiments provided in this application, it should be understood that the disclosed system, device, and method can be implemented in other ways. For example, the device embodiments described above are merely illustrative, for example, the division of the units is only a logical function division, and there may be other divisions in actual implementation, for example, multiple units or components may be combined or It can be integrated into another system, or some features can be ignored or not implemented. In addition, the displayed or discussed mutual coupling or direct coupling or communication connection may be indirect coupling or communication connection through some interfaces, devices or units, and may be in electrical, mechanical or other forms.

所述作为分离部件说明的单元可以是或者也可以不是物理上分开的，作为单元显示的部件可以是或者也可以不是物理单元，即可以位于一个地方，或者也可以分布到多个网络单元上。可以根据实际的需要选择其中的部分或者全部单元来实现本实施例方案的目的。The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the objectives of the solutions of the embodiments.

另外，在本申请各个实施例中的各功能单元可以集成在一个处理单元中，也可以是各个单元单独物理存在，也可以两个或两个以上单元集成在一个单元中。In addition, the functional units in the various embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units may be integrated into one unit.

所述功能如果以软件功能单元的形式实现并作为独立的产品销售或使用时，可以存储在一个计算机可读取存储介质中。基于这样的理解，本申请的技术方案本质上或者说对现有技术做出贡献的部分或者该技术方案的部分可以以软件产品的形式体现出来，该计算机软件产品存储在一个存储介质中，包括若干指令用以使得一台计算机设备(可以是个人计算机，服务器，或者网络设备等)执行本申请各个实施例所述方法的全部或部分步骤。而前述的存储介质包括：U盘、移动硬盘、只读存储器(Read-Only Memory，ROM)、随机存取存储器(Random Access Memory，RAM)、磁碟或者光盘等各种可以存储程序代码的介质。If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer readable storage medium. Based on this understanding, the technical solution of the present application essentially or the part that contributes to the existing technology or the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including Several instructions are used to make a computer device (which may be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the methods described in the various embodiments of the present application. The aforementioned storage media include: U disk, mobile hard disk, read-only memory (Read-Only Memory, ROM), random access memory (Random Access Memory, RAM), magnetic disk or optical disk and other media that can store program code .

以上所述，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以所述权利要求的保护范围为准。The above are only specific implementations of this application, but the protection scope of this application is not limited to this. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed in this application. Should be covered within the scope of protection of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims

一种线缆绝缘阻抗检测方法，其特征在于，所述方法由逆变器执行，所述逆变器的输出电连接至多条交流线缆，所述方法包括：A cable insulation resistance detection method, characterized in that the method is executed by an inverter, the output of the inverter is electrically connected to a plurality of AC cables, and the method includes:

将所述多条交流线缆中的待测交流线缆与所述逆变器的直流母线断开，并执行直流侧对地绝缘阻抗检测程序，以检测得到第一阻抗Riso1；Disconnect the AC cable to be tested among the plurality of AC cables from the DC bus of the inverter, and execute the DC side-to-ground insulation impedance detection program to detect the first impedance Riso1;

将所述待测交流线缆与所述直流母线的正极或负极电连通，并执行所述直流侧对地绝缘阻抗检测程序，以检测得到第二阻抗Riso2；Electrically connect the AC cable to be tested with the positive or negative pole of the DC bus, and execute the DC side-to-ground insulation impedance detection program to detect the second impedance Riso2;

根据所述Riso1和所述Riso2，确定所述待测交流线缆的对地绝缘阻抗。According to the Riso1 and the Riso2, the insulation resistance to the ground of the AC cable to be tested is determined.
如权利要求1所述的方法，其特征在于，所述待测交流线缆为对应于所述逆变器的一相输出的交流线缆，其中，所述第二阻抗Riso2为Riso1//R3，其中//表示阻抗并运算，R3为所述待测交流线缆的对地绝缘阻抗，The method of claim 1, wherein the AC cable to be tested is an AC cable corresponding to the one-phase output of the inverter, wherein the second impedance Riso2 is Riso1//R3 , Where // represents impedance and operation, R3 is the insulation impedance to ground of the AC cable under test,

所述根据所述Riso1和所述Riso2，确定所述待测交流线缆的对地绝缘阻抗，包括：The determining the insulation resistance to ground of the AC cable under test according to the Riso1 and the Riso2 includes:

根据如下方式计算R3：Calculate R3 as follows:

R3＝Riso1×Riso2/(Riso1-Riso2)。R3=Riso1×Riso2/(Riso1-Riso2).
如权利要求1所述的方法，其特征在于，所述待测交流线缆为对应于所述逆变器的两相输出的两条交流线缆，其中，所述第二阻抗Riso2为Riso1//R3//R4，其中//表示阻抗并运算，R3为所述两条交流线缆中一条交流线缆的对地绝缘阻抗，R4为所述两条交流线缆中另一条交流线缆的对地绝缘阻抗，The method according to claim 1, wherein the AC cables to be tested are two AC cables corresponding to the two-phase output of the inverter, wherein the second impedance Riso2 is Riso1/ /R3//R4, where // represents impedance and operation, R3 is the insulation impedance of one of the two AC cables to ground, and R4 is the insulation impedance of the other of the two AC cables Insulation resistance to ground,

所述根据所述Riso1和所述Riso2，确定所述待测交流线缆的对地绝缘阻抗，包括：The determining the insulation resistance to ground of the AC cable under test according to the Riso1 and the Riso2 includes:

根据如下方式计算所述两条交流线缆的总的对地绝缘阻抗R3//R4：Calculate the total insulation resistance R3//R4 of the two AC cables to the ground according to the following method:

R3//R4＝Riso1*Riso2/(Riso1-Riso2)。R3//R4=Riso1*Riso2/(Riso1-Riso2).
如权利要求1至3任一项所述的方法，其特征在于，在所述检测得到第一阻抗Riso1之后，还包括：The method according to any one of claims 1 to 3, wherein after the first impedance Riso1 is obtained by the detection, the method further comprises:

确定所述Riso1大于或等于第一阈值。It is determined that the Riso1 is greater than or equal to the first threshold.
如权利要求1至4中任一项所述的方法，其特征在于，还包括：The method according to any one of claims 1 to 4, further comprising:

若所述待测交流线缆的对地绝缘阻抗值小于第二阈值，则生成告警信息；或者If the insulation resistance to ground of the AC cable to be tested is less than the second threshold, generate alarm information; or

若所述待测交流线缆对地绝缘阻抗值大于或等于第二阈值，则生成表示所述待测交流线缆对地绝缘阻抗值正常的信息。If the insulation resistance value of the AC cable to ground is greater than or equal to the second threshold value, information indicating that the insulation resistance value of the AC cable to ground is normal is generated.
一种线缆绝缘阻抗检测方法，其特征在于，所述方法由逆变器执行，所述逆变器的输出通过并网开关电连接至交流线缆，所述方法包括：A cable insulation resistance detection method, characterized in that the method is executed by an inverter, the output of the inverter is electrically connected to an AC cable through a grid-connected switch, and the method includes:

导通所述交流线缆中任意两相交流线缆对应的并网开关，并对所述两相交流线缆中的第一相交流线缆对应的第一滤波电容充电；Turn on the grid-connecting switch corresponding to any two-phase AC cable in the AC cable, and charge the first filter capacitor corresponding to the first-phase AC cable in the two-phase AC cable;

以所述第一滤波电容作为激励源，对所述两相交流线缆中的第二相交流线缆对应的第二滤波电容充电；Using the first filter capacitor as an excitation source to charge a second filter capacitor corresponding to a second-phase AC cable in the two-phase AC cable;

检测所述第一滤波电容和所述第二滤波电容上的电压；Detecting the voltage on the first filter capacitor and the second filter capacitor;

根据所述第一滤波电容和所述第二滤波电容上的电压，确定所述两相交流线缆之间的相间绝缘阻抗。Determine the phase-to-phase insulation impedance between the two-phase AC cables according to the voltage on the first filter capacitor and the second filter capacitor.
如权利要求6所述的方法，其特征在于，所述确定所述两相交流线缆之间的相间绝缘阻抗包括：The method according to claim 6, wherein the determining the phase-to-phase insulation resistance between the two-phase AC cables comprises:

按照如下方式确定所述相间绝缘阻抗：Determine the insulation resistance between phases as follows:

-t/(Cb×ln(1-Ub/Ua))，-t/(Cb×ln(1-Ub/Ua)),

其中，t为对所述第二滤波电容充电的时间，Cb为所述第二滤波电容值，Ub为所述第二滤波电容上的电压，Ua为所述第一滤波电容上的电压；或者，Where t is the time to charge the second filter capacitor, Cb is the second filter capacitor value, Ub is the voltage on the second filter capacitor, and Ua is the voltage on the first filter capacitor; or ,

按照如下方式确定所述相间绝缘阻抗：Determine the insulation resistance between phases as follows:

根据所述第一滤波电容上的电压、所述第二滤波电容上的电压和所述漏电流传感器检测的电流I确定所述相间绝缘阻抗。The interphase insulation resistance is determined according to the voltage on the first filter capacitor, the voltage on the second filter capacitor, and the current I detected by the leakage current sensor.
如权利要求6或7所述的方法，其特征在于，在对所述两相交流线缆中的第一相交流线缆对应的第一滤波电容充电之前，所述方法还包括：The method according to claim 6 or 7, characterized in that, before charging the first filter capacitor corresponding to the first phase AC cable in the two-phase AC cable, the method further comprises:

控制所述逆变器的直流母线的电压值大于或等于电网线电压不控整流值。Control the voltage value of the DC bus of the inverter to be greater than or equal to the uncontrolled rectification value of the grid line voltage.
如权利要求6至7中任一项所述的方法，其特征在于，还包括：The method according to any one of claims 6 to 7, further comprising:

若所述相间绝缘阻抗值小于第三阈值，则生成告警信息；或者，If the phase-to-phase insulation resistance value is less than the third threshold, an alarm message is generated; or,

若所述相间绝缘阻抗值大于或等于第三阈值，则生成表示所述相间绝缘阻抗值正常的信息。If the interphase insulation resistance value is greater than or equal to the third threshold value, information indicating that the interphase insulation resistance value is normal is generated.
一种线缆绝缘阻抗检测装置，其特征在于，所述装置置于逆变器中，所述逆变器的输出电连接至多条交流线缆，所述装置包括：A cable insulation resistance detection device, characterized in that the device is placed in an inverter, the output of the inverter is electrically connected to a plurality of AC cables, and the device includes:

控制器，用于控制将所述多条交流线缆中的待测交流线缆与所述逆变器的直流母线断开，并执行直流侧对地绝缘阻抗检测程序，根据检测电路检测结果计算得到第一阻抗Riso1；The controller is used to control the disconnection of the AC cable to be tested among the plurality of AC cables from the DC bus of the inverter, and execute the DC side-to-ground insulation impedance detection program, and calculate according to the detection result of the detection circuit Obtain the first impedance Riso1;

所述控制器还用于控制将所述待测交流线缆与所述直流母线的正极或负极电连通，并执行所述直流侧对地绝缘阻抗检测程序，根据检测电路检测结果计算得到第二阻抗Riso2；The controller is also used to control the electrical connection between the AC cable to be tested and the positive or negative pole of the DC bus, and execute the DC side-to-ground insulation impedance detection program, and calculate the second Impedance Riso2;

所述控制器还用于根据所述Riso1和所述Riso2，确定所述待测交流线缆的对地绝缘阻抗。The controller is further configured to determine the insulation resistance to ground of the AC cable to be tested according to the Riso1 and the Riso2.
如权利要求10所述的装置，其特征在于，所述待测交流线缆为对应于所述逆变器的一相输出的交流线缆，其中，所述第二阻抗Riso2为Riso1//R3，其中//表示阻抗并运算，R3为所述待测交流线缆的对地绝缘阻抗，The device of claim 10, wherein the AC cable to be tested is an AC cable corresponding to one-phase output of the inverter, wherein the second impedance Riso2 is Riso1//R3 , Where // represents impedance and operation, R3 is the insulation impedance to ground of the AC cable under test,

所述控制器还用于根据所述Riso1和所述Riso2，确定所述待测交流线缆的对地绝缘阻抗，包括：The controller is further configured to determine the insulation resistance to ground of the AC cable to be tested according to the Riso1 and the Riso2, including:

根据如下方式计算R3：Calculate R3 as follows:

R3＝Riso1×Riso2/(Riso1-Riso2)。R3=Riso1×Riso2/(Riso1-Riso2).
如权利要求10所述的装置，其特征在于，所述待测交流线缆为对应于所述逆变器的两相输出的两条交流线缆，其中，所述第二阻抗Riso2为Riso1//R3//R4，其中//表示阻抗并运算，R3为所述两条交流线缆中一条交流线缆的对地绝缘阻抗，R4为所述两条交流线缆中另一条交流线缆的对地绝缘阻抗，The device according to claim 10, wherein the AC cables to be tested are two AC cables corresponding to the two-phase output of the inverter, wherein the second impedance Riso2 is Riso1/ /R3//R4, where // represents impedance and operation, R3 is the insulation impedance of one of the two AC cables to ground, and R4 is the insulation impedance of the other of the two AC cables Insulation resistance to ground,

所述控制器还用于根据所述Riso1和所述Riso2，确定所述待测交流线缆的对地绝缘阻抗，包括：The controller is further configured to determine the insulation resistance to ground of the AC cable to be tested according to the Riso1 and the Riso2, including:

根据如下方式计算所述两条交流线缆的总的对地绝缘阻抗R3//R4：Calculate the total insulation resistance R3//R4 of the two AC cables to the ground according to the following method:

R3//R4＝Riso1*Riso2/(Riso1-Riso2)。R3//R4=Riso1*Riso2/(Riso1-Riso2).
如权利要求10至12中任一项所述的装置，其特征在于，在所述根据检测电路检测检测结果计算得到第一阻抗Riso1之后，还包括：The device according to any one of claims 10 to 12, wherein after the first impedance Riso1 is calculated according to the detection result of the detection circuit, it further comprises:

确定所述Riso1大于或等于第一阈值。It is determined that the Riso1 is greater than or equal to the first threshold.
如权利要求10至13中任一项所述的装置，其特征在于，还包括：The device according to any one of claims 10 to 13, further comprising:

若所述待测交流线缆的对地绝缘阻抗值小于第二阈值，则生成告警信息；或者If the insulation resistance to ground of the AC cable to be tested is less than the second threshold, generate alarm information; or

若所述待测交流线缆对地绝缘阻抗值大于或等于第二阈值，则生成表示所述待测交流线缆对地绝缘阻抗值正常的信息。If the insulation resistance value of the AC cable to ground is greater than or equal to the second threshold value, information indicating that the insulation resistance value of the AC cable to ground is normal is generated.
一种线缆绝缘阻抗检测装置，其特征在于，所述装置置于逆变器中，所述逆变器的输出电连接至交流线缆，所述装置包括：A cable insulation resistance detection device, characterized in that the device is placed in an inverter, the output of the inverter is electrically connected to an AC cable, and the device includes:

控制器，用于控制所述交流线缆中任意两相交流线缆对应的并网开关导通，并控制所述两相交流线缆中的第一相交流线缆对应的第一滤波电容充电；The controller is used to control the grid connection switch corresponding to any two-phase AC cable in the AC cable to be turned on, and to control the charging of the first filter capacitor corresponding to the first-phase AC cable in the two-phase AC cable ；

所述控制器还用于控制所述第一滤波电容作为激励源，对所述两相交流线缆中的第二相交流线缆对应的第二滤波电容充电；The controller is further configured to control the first filter capacitor as an excitation source to charge a second filter capacitor corresponding to a second-phase AC cable in the two-phase AC cable;

检测电路，用于检测所述第一滤波电容和所述第二滤波电容上的电压；A detection circuit for detecting the voltage on the first filter capacitor and the second filter capacitor;

所述控制器还用于根据所述第一滤波电容和所述第二滤波电容上的电压，确定所述两相交流线缆之间的相间绝缘阻抗。The controller is further configured to determine the phase-to-phase insulation impedance between the two-phase AC cables according to the voltage on the first filter capacitor and the second filter capacitor.
如权利要求15所述的装置，其特征在于，所述确定所述两相交流线缆之间的相间绝缘阻抗包括：The device according to claim 15, wherein said determining the phase-to-phase insulation resistance between the two-phase AC cables comprises:

按照如下方式确定所述相间绝缘阻抗：Determine the insulation resistance between phases as follows:

-t/(Cb×ln(1-Ub/Ua))，-t/(Cb×ln(1-Ub/Ua)),

其中，t为对所述第二滤波电容充电的时间，Cb为所述第二滤波电容值，Ub为所述第二滤波电容上的电压，Ua为所述第一滤波电容上的电压；或者，Where t is the time to charge the second filter capacitor, Cb is the second filter capacitor value, Ub is the voltage on the second filter capacitor, and Ua is the voltage on the first filter capacitor; or ,

按照如下方式确定所述相间绝缘阻抗：Determine the insulation resistance between phases as follows:

根据所述第一滤波电容上的电压、所述第二滤波电容上的电压和所述漏电流传感器检测的电流I确定。It is determined according to the voltage on the first filter capacitor, the voltage on the second filter capacitor, and the current I detected by the leakage current sensor.
如权利要求15或16所述的装置，其特征在于，在所述控制器控制所述两相交流线缆中的第一相交流线缆对应的第一滤波电容充电之前，还包括：The device according to claim 15 or 16, wherein before the controller controls the charging of the first filter capacitor corresponding to the first-phase AC cable in the two-phase AC cable, the method further comprises:

控制所述逆变器的直流母线的电压值大于或等于电网线电压不控整流值。Control the voltage value of the DC bus of the inverter to be greater than or equal to the uncontrolled rectification value of the grid line voltage.
如权利要求15至17中任一项所述的装置，其特征在于，还包括：The device according to any one of claims 15 to 17, further comprising:

若所述相间绝缘阻抗值小于第三阈值，则生成告警信息；或者，If the phase-to-phase insulation resistance value is less than the third threshold, an alarm message is generated; or,

若所述相间绝缘阻抗值大于或等于第三阈值，则生成表示所述相间绝缘阻抗值正常的信息。If the interphase insulation resistance value is greater than or equal to the third threshold value, information indicating that the interphase insulation resistance value is normal is generated.