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EP-3696939-B1 - EARTHING SYSTEM AND METHOD FOR DISSIPATING ALTERNATING CURRENT FROM A STEEL STRUCTURE

EP3696939B1EP 3696939 B1EP3696939 B1EP 3696939B1EP-3696939-B1

Inventors

  • KAISER, FRANK
  • Korupp, Karl
  • ZIMMER, WALDEMAR

Dates

Publication Date
20260513
Application Date
20200217

Claims (13)

  1. Earthing installation for dissipating alternating current from a steel structure (2), wherein the earthing installation (1) has an earthing electrode (7) which is electrically connected to the steel construction (2), wherein the steel construction (2) is in the form of an underground cathodically protected pipeline which is influenced with alternating current, wherein a delimitation unit (12) is electrically connected to the steel construction (2) and the earthing electrode (7) and brings about a direct-current separation of the steel construction (2) from the earthing electrode (7), wherein the earthing installation has a transformer component (9) with a primary coil and a secondary coil, wherein the dissipated alternating current can be fed into the primary coil, wherein the primary coil is connected in series in the current path of the earthing installation, wherein the secondary winding provides the charging voltage for an accumulator (10) and wherein a measurement value detection unit (11) is configured to continuously or periodically detect and continuously or periodically store current and voltage values of the delimitation unit (12).
  2. Earthing installation according to claim 1, characterized in that the secondary winding of the transformer component (9) is electrically connected to an electronic charging unit which is configured to set and/or adjust the operating voltage of the accumulator and/or in that the transformer component (9) can be adapted to different alternating-current ranges.
  3. Earthing installation according to at least one of the preceding claims, characterized in that a voltage transformer which is preferably adjustable is connected to the accumulator (10).
  4. Earthing installation according to any one of the preceding claims, characterized in that the measurement value detection unit (11) which is supplied with power by the accumulator (10) is configured to continuously or periodically measure and store current and voltage values of the earthing installation.
  5. Earthing installation according to claim 4, characterized in that a communication unit (13) is in communicating connection with the measurement value detection unit (11) and a remote monitoring unit (14).
  6. Earthing installation according to claim 4 or 5, characterized in that the measurement value detection unit (11) or the remote monitoring unit (14) is configured to display the dissipated alternating-current voltage and/or to calculate and display the resistance values which are characterizing for the functionality of the earthing installation from the measured voltage and current measurement values and/or to compare them with desired values.
  7. Earthing installation according to any one of claims 4 to 6, characterized in that the measurement value detection unit or the remote monitoring unit (14) is configured to calculate at least the earthing propagation resistance of the earthing installation (1), in that an auxiliary earthing (8) is connected in parallel to the earthing installation (1), in that the earthing installation (1) has a first current measurement resistor (15) on which the overall alternating current flowing over the earthing installation (1) can be measured, in that the measurement value detection unit (11) is configured to measure the alternating-current voltage between the earthing electrode (7) and the steel construction (2) and the alternating-current voltage between the earthing electrode (7) and the auxiliary earthing (8) and in that the measurement value detection unit or the remote monitoring unit (14) is configured to calculate the earthing propagation resistance of the earthing installation (19) from the difference of the measured alternating-current voltages divided by the measured overall alternating current.
  8. Earthing installation according to claim 1, characterized in that the measurement value detection unit (11) is configured to measure and store current and voltage values of the delimitation unit (12), in that the measurement value detection unit or the remote monitoring unit (14) is configured to calculate and display the resistance values which are characterizing for the functionality of the delimitation unit (12) from the measured voltage and current measurement values and/or to compare them with desired values.
  9. Earthing installation according to claim 1, characterized in that the delimitation unit (12) has a first delimitation module (12a) and a second delimitation module (12b) connected parallel thereto, in that the first delimitation module (12a) is in the form of a series resonant circuit, in that the second delimitation module (12b) has a switch (12b') which closes when an alternating-current voltage which is induced in the pipeline exceeds a set alternating-current voltage threshold value, in that a second current measurement resistor (16) is located in the first delimitation module (12a) which is in the form of a series resonant circuit, and in that the measurement value detection unit (11) is configured to measure the alternating-current voltage across the earthing installation, the overall alternating current flowing over the earthing installation (1) on the first current measurement resistor (15) and the partial alternating current flowing over the first delimitation module (12a) on the second current measurement resistor (16), and in that the measurement value detection unit (11) or the remote monitoring unit (14) is configured to calculate the internal resistance of the first delimitation module (12a) from the alternating-current voltage of the earthing installation (1) divided by the partial alternating current and to calculate the internal resistance of the second delimitation module (12b) from the alternating-current voltage divided by the overall alternating current of the earthing installation (1).
  10. Earthing installation according to any one of claims 1 or 9, characterized in that the measurement value detection unit (11) is additionally configured at the first current measurement resistor (15) to measure the overall direct current flowing over the earthing installation (1) and/or at the second current measurement resistor (16) to measure the partial direct current flowing over the first delimitation module (12a) and in that the remote monitoring unit (14) is configured to display the measured direct current values for identifying direct current leakage currents.
  11. Method for dissipating alternating current from a steel construction by means of at least one earthing installation, wherein the earthing installation (1) has an earthing electrode (7) which is electrically connected to the steel construction (2), wherein the steel construction (2) is in the form of an underground cathodically protected pipeline which is influenced with alternating current and has a delimitation unit (12) which is electrically connected to the steel construction (2) and the earthing electrode (7) and brings about a direct-current separation of the steel construction (2) from the earthing electrode (7), wherein the earthing installation (1) is electrically connected to a transformer component (9) having a primary winding and a secondary winding, wherein the primary winding is connected in series in the current path of the earthing installation, wherein the alternating current which is dissipated from the earthing installation (1) is fed into the primary winding of the transformer component (9) and wherein the secondary winding provides the charging voltage for an accumulator (10) and wherein by means of a measurement value detection unit (11) current and voltage values of the delimitation unit (12) are continuously or periodically detected and continuously or periodically stored.
  12. Method according to claim 11, characterized by the following steps, - continuously detecting and storing current and voltage values of the earthing installation (1) in situ by means of at least the measurement value detection unit (11) which is supplied with power by means of the accumulator (10), - transmitting the measurement values to a remote monitoring unit (14) by means of a communication unit (13), - displaying the alternating-current voltage which influences the steel construction (2) or displaying the dissipated alternating current and/or - calculating resistance values which are characterizing for the functionality of the earthing installation (1) from the transmitted current and voltage measurement values and displaying the calculated resistance values and/or comparing the calculated resistance values with desired values by means of the remote monitoring unit.
  13. Method according to claim 12, characterized in that the communication unit transmits the measurement values of the measurement value detection unit (11) to the remote monitoring unit (14) and in that the remote monitoring unit (14) is configured to calculate and display the resistance values which are characterizing for the functionality of the delimitation unit (12) from the measured voltage and current measurement values and/or to compare them with desired values.

Description

The invention relates to an earthing system for discharging alternating current from a steel structure, wherein the earthing system has an earthing electrode that is electrically connected to the steel structure. Furthermore, the invention relates to a method for discharging alternating current from a steel structure by means of at least one earthing system, wherein the earthing system has an earthing electrode that is electrically connected to the steel structure, wherein the steel structure is designed as a buried, cathodically protected pipeline subjected to alternating current. The CN 106 707 098 A This document discloses an online monitoring device used for the online monitoring and positioning of overhead line discharges, i.e., for fault location in overhead lines. The online monitoring device includes a transformer component for monitoring the current of the grounding wire of a steel structure. For monitoring purposes, the grounding wire or electrode of the steel structure passes through a magnetic ring of the transformer component. The CN 106 597 113 A This shows an online testing device for the earth resistance of a power pole. The online testing device is designed to simplify earth resistance measurement, in particular enabling measurements without having to disconnect the grounding conductor. Two parallel grounding conductors are each equipped with a sensing head. An additional auxiliary electrode is located in the ground. An upper coil, a lower coil, and the auxiliary electrode are connected to a signal processing module for control and data processing. The grounding conductors run through the center of each coil. The DE 25 46 694 A1 Figure 1 shows a measuring transmitter for high-voltage power lines. A conversion-digitization unit assigns digital values to the operating potential of the high-voltage line conductor. One or more electrical or non-electrical quantities from the high-voltage line, fed to a high-frequency transmitter unit, are converted into a high-frequency signal. This signal is then transmitted directionally, omnidirectionally, or along the high-voltage line using a suitable antenna. The energy required for operation is supplied to the conversion-digitization unit and the high-frequency transmitter unit (with its suitable antenna) by a power supply unit, which is powered by current in the high-voltage line conductor. The power supply unit includes a ring transformer, so that the high-voltage line conductor acts as the primary winding. The voltage induced in the secondary winding is converted into DC voltage with the high-voltage line conductor's operating potential as the zero potential by suitable rectifier circuits. A battery is used to keep the voltage constant; it is charged whenever the current in the high-voltage line is large enough. High-voltage overhead power lines couple alternating voltages into steel structures through their electromagnetic fields. This can result in high contact voltages between the steel structure and the ground. During peak load times, earth faults, or in cases of asymmetry between parallel high-voltage overhead power lines, the voltages coupled into a steel structure can reach high values. Therefore, grounding systems are used to protect people and animals. For pipelines, grounding is mandatory to limit the permanently present touch voltage to values < 60V for the protection of personnel. To limit the touch voltage in the case of continuous exposure, i.e. electromagnetically coupled touch voltages, earthing systems can be used that are directly connected to the steel structure. An earthing system has at least one earthing electrode, i.e., an electrically conductive element that is in electrical contact with the earth in order to dissipate the alternating current and to limit the alternating voltage, for example, of a pipeline. In practice, earthing systems are manually checked on site at regular intervals to ensure they are functioning correctly, i.e., to verify that the essential components of the earthing system are working as intended. Each grounding system must be inspected on-site by qualified personnel to verify its functionality. Because individual grounding systems can be located far apart, this on-site inspection is very labor-intensive. In practice, to test the earthing system on-site, a resistance measuring device is connected to its circuits. This requires intervention in the electrical circuits. Consequently, the effort required for on-site testing is relatively high. Due to the increasing generation of renewable electricity and the monitoring of high-voltage transmissions, the factors that determine the effects of high voltage on steel structures, especially pipelines, are highly variable. Therefore There is a need to be able to check at any time how high the alternating current influence of a steel structure is currently, in order to ensure that the earthing systems are functioning properly. For on-site measurements, a power supply