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EP-4487437-B1 - CONDITION MONITORING OF ELECTRONIC COMPONENTS IN ELECTRICAL POWER SYSTEMS

EP4487437B1EP 4487437 B1EP4487437 B1EP 4487437B1EP-4487437-B1

Inventors

  • ASOODAR, Mohsen
  • DANIELSSON, Christer

Dates

Publication Date
20260506
Application Date
20220301

Claims (14)

  1. A computer-implemented method for monitoring a converter (10) comprising a plurality of series-connected submodules (12) in an arm (14) of the converter, each submodule having electrical components arranged in a same circuit topology, the method comprising: determining (410) for each electrical component in a group, a component value for an electrical characteristic; wherein the group comprises a corresponding electrical component from each submodule, in the plurality of submodules, having a same position in the circuit topology of their respective submodule; determining (420), for the group of electrical components, a group value for the electrical characteristic, characterised in that the group value is an average of the component values; the method further comprising: determining (430) a deviation of the component value from the group value, for at least one electrical component in the group; and determining (440) a health status for said at least one electrical component of the group based on the determined deviation for the electrical component.
  2. The computer-implemented method according to claim 1, wherein: the group comprises electrical components from all of the submodules in the arm of the converter, or a subset thereof.
  3. The computer-implemented method according to claim 1 or claim 2, wherein: each submodule comprises a capacitor (110) and a plurality of semiconductor switches (120a, 120b, 120c, 120d); and the circuit topology is a half-bridge or a full-bridge submodule topology.
  4. The computer-implemented method according to claim 3, wherein: the corresponding electrical component is the capacitor (110); the group is a group of capacitors (110); and the electrical characteristic is capacitance.
  5. The computer-implemented method according to claim 4, wherein: the capacitance for each capacitor is determined based on: a capacitor voltage (v C ) of said each capacitor (110), and a group current of the group of capacitors, the group current being an arm current, flowing through the arm of the converter.
  6. The computer-implemented method according to claim 3, wherein: the corresponding electrical component is one of the plurality of semiconductor switches; the group is a group of corresponding semiconductor switches (120a, 120b, 120c, 120d); and the electrical characteristic is resistance.
  7. The computer-implemented method according to claim 6, wherein: the resistance for each corresponding semiconductor switch (120a, 120b, 120c, 120d) is determined based on: a collector-emitter voltage, a drain-source voltage, a gate-emitter voltage and/or a gate-source voltage of said each corresponding semiconductor switch, and/or a group current of the group of corresponding semiconductor switches, the group current being an arm current (i arm ), flowing through the arm of the converter.
  8. The computer-implemented method according to any preceding claim, wherein: the electrical characteristic is a temperature-dependent electrical characteristic.
  9. A computer-implemented method for monitoring an energy storage system (710) comprising a plurality of series-connected energy storage units, ESUs, 712, each ESU having electrical components arranged in a same circuit topology, the method comprising: determining, for each electrical component in a group, a component value for an electrical characteristic; wherein the group comprises a corresponding electrical component from each ESU, 712, in the plurality of ESUs, having a same position in the circuit topology of their respective ESU; determining, for the group of electrical components, a group value for the electrical characteristic, wherein the group value is an average of the component values; determining a deviation of the component value from the group value, for at least one electrical component in the group; and determining a health status for said at least one electrical component of the group based on the determined deviation for the electrical component.
  10. A control unit (620) comprising means for carrying out the method according to any of claims 1 to 8.
  11. A control unit (940, 960) comprising means for carrying out the method according to claim 9.
  12. A power station (910) comprising: a static synchronous compensator, STATCOM, suitable for a power grid, the STATCOM comprising at least one converter; and the control unit according to claim 10.
  13. The power station (910) according to claim 12, further comprising: an energy storage system (710) having a plurality of energy storage units (712); and the control unit according to claim 11.
  14. A computer-readable medium comprising instructions which, when executed by a computer, cause the computer to carry out the method according to any of claims 1 to 9.

Description

TECHNICAL FIELD The present disclosure relates to electrical power systems, such as MMCs or (E-)STATCOMs. More particularly, the present disclosure relates to a method for monitoring the condition of electronic components in electrical power systems. BACKGROUND Power stations may commonly comprise power electronic converter devices (e.g. voltage-source converter devices) that can act as either a source or sink of reactive AC power for a power grid. An example of such a device is a static synchronous compensator (STATCOM) or a modular multilevel converter (MMC) used in, for example, a high voltage direct current (HVDC) application. Some power stations may further comprise energy storage systems for storing electrical energy, e.g. such that electrical energy can be stored during times of electrical production surplus, and provided to the power grid during times of electrical production deficit. Power stations comprising STATCOM devices and energy storage systems may be referred to as employing 'enhanced' STATCOM, or 'E-STATCOM' devices. A converter may comprise a plurality of submodules connected in series, e.g. in one or more arms, such that if an arm of the converter has N submodules, the converter output voltage will have N+1 or 2N+1 levels (e.g. depending on whether submodules comprise half- or full-bridges, respectively), where each level is a voltage contribution for each step of the step-wise built output waveform for the converter (i.e. N levels of VSM plus zero, where VSM is a voltage contribution from a single submodule). Thus, typically, the more levels a converter has, the more a step-wise-built output waveform may approximate an AC waveform, for example. Submodules of such converters may typically comprise capacitors connected to modulated switches, these electronic components being arranged in e.g. a half-bridge or full-bridge configuration. The switches may be modulated (e.g. by a converter control unit) in such a way as to switch the capacitors into and out of a contribution to a voltage output of the converter so as to build an output waveform in a stepwise fashion. The modulation scheme may be configured such that the output waveform approximates an AC waveform. An energy storage system may comprise a plurality of energy storage units (ESUs) connected in series, e.g. in one or more strings, wherein each ESU may comprise a battery management system (BMS), which may also be referred to as an energy storage management system (ESMS), configured to balance the amounts of stored electrical energy between ESUs in a string. The BMS may comprise a capacitor and a balancing resistor, which may be engaged via a balancing switch. In electrical power systems, the electrical components (e.g. in submodules and/or ESUs) may be subject to high voltages and high currents, especially in high voltage direct current (HVDC) applications. Hence, degradation of these components can be expected under these conditions. Condition monitoring of such high-power components may thus be desired. Condition monitoring may, for example, improve an understanding of the current operational state of such high-power components. Moreover, 'online' condition monitoring (i.e. monitoring whilst components are in use) can help identify where maintenance may be needed, and how urgent the maintenance work may be. US 10 473 728 B2 discloses a possibility to determine the states of charge and energy levels of the energy stores using a small number of measuring systems for easier operation of multilevel converters. Furthermore, in the paper "Monitoring transistor degradation in power electronic converters using saturation-region resistance" by Ren Lei et al. a health monitoring method using the saturation-region resistance is proposed to identify the level of aging associated with power semiconductor switches is disclosed. Finally, EP 3 133 710 A1 concerns a Modular Multilevel power Converter (MMC) Statcom with an extended preferred application range or power rating. SUMMARY The invention refers to a computer-implemented method for monitoring a converter, according to claim 1, a computer-implemented method for monitoring an energy storage system, according to claim 9, control units, according to the claims 10 and 11, a power station, according to claim 12, and a computer-readable medium, according to claim 14. Preferred embodiments are defined in the dependent claims. It is therefore an object of the present disclosure to provide an improved monitoring of the condition of electronic components in electrical power systems. In particular, and as a particular advantage of the presently disclosed approach, an accurate monitoring technique is provided without requiring additional hardware. This and other objects are achieved by means of a method as defined in the appended independent claims. Other embodiments are defined by the dependent claims. According to an aspect of the present disclosure, there is provided a computer-implemented method fo