Method and device for insulation monitoring of a water-electrolysis installation

Patent metadata

Field	Value
Publication number	US-12399208-B2
Application number	US-202418791601-A
Country	US
Kind code	B2
Filing date	Aug 1, 2024
Priority date	Jul 27, 2023
Publication date	Aug 26, 2025
Grant date	Aug 26, 2025

Abstract

A method and an electrical circuit arrangement is for determining an insulation resistance of an ungrounded power supply system, which feeds electrical energy to the water-electrolysis installation. The fundamental idea of the method is based on predicting the insulation resistance of the ungrounded power supply system during an initial booting of the water-electrolysis installation and thus keeping the delay caused by the demineralization process as short as possible until the electrolysis process for subsequent booting processes of the electrolysis installation has been actually cleared. In a variation of the method, the electric conductance value and the temperature of the process water are additionally provided and recorded depending on the specific installation by the demineralization installation during the demineralization process. The result is a cost-efficient monitoring approach with a simple option for retrofitting for determining the insulation resistance of the ungrounded power supply system for the supply of water-electrolysis installations.

First claim

The invention claimed is:

1. A method for determining an insulation resistance R iso of an ungrounded power supply system ( 20 ), which feeds electrical energy to a water-electrolysis installation ( 2 ), the method comprising the steps:
initially booting (S 1 ) the water-electrolysis installation ( 2 ) starting with a demineralization process until a steady state of the demineralization of the process water has been achieved;
during the demineralization process, measuring and saving a number of total insulation-resistance values R toti at specific registration times t i by means of an insulation monitoring device (IMD), which feeds a measuring current I m driven by a measuring voltage U m to the ungrounded power supply system ( 20 );
measuring measuring-current portions I w1 , I w2 in an process-water pipe system ( 12 , 14 ) by means of highly sensitive current sensors ( 32 ) in the steady state of the demineralization;
computing and storing insulation resistance R iso from measuring voltage U m , registered measuring-current portions I w1 , I w2 and measuring current I m in the steady state of the demineralization;
computing process-water resistance values R wi from total insulation-resistance values R toti and insulation resistance R iso for registration times t i based on a modeling of a parallel circuit formed by process-water resistance values R wi and insulation resistance R iso ;
computing a regression curve R w (t) for process-water resistance R w ,
an expected insulation-resistance value R′ iso (T) being computed in subsequent regular booting processes (S 2 ) for a temporally consecutive determination time T during the demineralization process, starting from a regression value R w (t) at respective determination time T and from a current total insulation-resistance value R tot (T) measured by means of the insulation monitoring device (IMD) at respective determination time T; and
the water-electrolysis installation ( 2 ) being cleared as soon as expected insulation-resistance value R′ iso (T) has exceeded a predetermined threshold value R lim in the progression of the continuous computation.

2. The method according to claim 1 , wherein the number of registration times t i and their temporal interval allow a sufficiently precise modeling via the regression curve R w (t).

3. The method according to claim 1 , wherein several temperature-adapted regression curves R w (t) are computed as a function of an process-water temperature ϑ.

4. The methods according to claim 1 , wherein measuring-current portions I w1 , I w2 are measured by highly sensitive current sensors in the μA to mA range.

5. The methods according to claim 1 , wherein a direct current I DC1 , I DC2 is measured in the process-water pipe system ( 12 , 14 ).

6. The method according to claim 5 , wherein direct current I DC1 , I DC2 is measured in the process-water pipe system ( 12 , 14 ) in the single-digit ampere range to a magnitude of over 100 Amperes by means of robust current sensors.

7. The methods according to claim 1 , wherein the water-electrolysis installation ( 2 ) is only cleared should direct current I DC1 , I DC2 not exceed a predetermined value.

8. An electrical circuit arrangement ( 30 ) for determining an insulation resistance R iso of an ungrounded power supply system ( 20 ), which feeds electrical energy to a water-electrolysis installation ( 2 ),
the electrical circuit arrangement ( 30 ) having an insulation monitoring device (IMD) according to product standard IEC 61557-8 which serves for measuring and storing a number of total insulation-resistance values R toti and is adapted to execute the method of claim 1 , and having a highly sensitive current sensor ( 32 ) disposed in both an process-water supply pipe ( 12 ) and an process-water drain pipe ( 14 ).

9. The electrical circuit arrangements according to claim 8 , wherein the highly sensitive current sensors for measuring measuring-current portions I w1 , I w2 are designed as current sensor technology for measurements in the range of μA to mA.

10. The electrical circuit arrangements according to claim 8 , wherein a robust current sensor technology serves for measuring a direct current I DC in the process-water pipe system ( 12 , 14 ) and is designed for measurements in the single-digit ampere range to a magnitude of over 100 Amperes.

11. A method for determining an insulation resistance R iso of an ungrounded power supply system ( 20 ), which feeds electrical energy to a water-electrolysis installation ( 2 ), the method comprising the following steps:
initially booting (S 1 ) the water-electrolysis installation ( 2 ) starting with a demineralization process until a steady state of the demineralization of the process water has been achieved;
during the demineralization process, measuring and storing a number of total insulation resistances R toti at specific registration times t i by means of an insulation monitoring device (IMD), which feeds a measuring current I m driven by a measuring voltage U m to the ungrounded power supply system ( 20 ), as well as measuring and storing electric conductance values S i of the process water and of temperature values ϑ i of the process water;
measuring measuring-current portions I w1 , I w2 in an process-water pipe system ( 12 , 14 ) by means of highly sensitive current sensors ( 32 ) in the steady state of the demineralization;
computing and storing insulation resistance R iso from measuring voltage U m , registered measuring-current portions I w1 , I w2 and measuring current I m in the steady state of the demineralization;
computing process-water resistance values R wi from total insulation-resistance values R toti and insulation resistance R iso for registration times t i based on a modeling of a parallel circuit formed by process-water resistance values R wi and insulation resistance R iso ;
computing a time-independent function R w (R tot , S, ϑ) for process-water resistance R w ,
an expected insulation resistance R′ iso (T) being computed in subsequent regular booting processes for a temporally consecutive determination time T during the demineralization phase, starting from process-water resistance R w (T) given by time-independent function R w (R tot , S, ϑ) at respective determination time T and from a current total insulation-resistance value R tot (T) measured by means of the insulation monitoring device (IMD) at the respective determination time T; and
the water-electrolysis installation ( 2 ) being cleared as soon as expected insulation-resistance R′ iso (T) has exceeded a predetermined threshold value R lim in the progression of the continuous computation.

12. The method according to claim 11 , wherein the number of registration times t i and their temporal interval allow a description of process-water resistance R w as a function of the recorded values total insulation-resistance value R toti , electric conductance value S i and temperature value ϑ i via a time-independent function R w (R tot , S, ϑ).

13. An electrical circuit arrangement ( 30 ) for determining an insulation resistance R iso of an ungrounded power supply system ( 20 ), which feeds electrical energy to a water-electrolysis installation,
the electrical circuit arrangement ( 30 ) having an insulation monitoring device (IMD) according to product standard IEC 61557-8 which serves for measuring and storing a number of total insulation-resistance values R toti and is adapted to execute the method of claim 11 , and having a highly sensitive current sensor ( 32 ) disposed in both an process-water supply pipe ( 12 ) and an process-water drain pipe ( 14 ).

Assignees

• Bender Gmbh & Co Kg

Inventors

• Hackl Dieter

Classifications

• G01R31/40

  Testing power supplies (testing photovoltaic devices H02S50/10) · CPC title

• G01R27/22

  Measuring resistance of fluids · CPC title

• G01R27/025

  Measuring very high resistances, e.g. isolation resistances, i.e. megohm-meters · CPC title

• G01R31/1272 Primary

  of cable, line or wire insulation, e.g. using partial discharge measurements (locating faults in cables G01R31/083) · CPC title

• C25B1/04 Primary

  by electrolysis of water · CPC title