OMICRON - Your partner for all renewable energy sources
The renewable energy transition poses significant challenges for the electricity sector. On the one hand, increasing demand for electrical energy (due to electrification of e.g. mobility and heating) and, on the other hand, replacing existing fossil fuel power plants with renewable energy resources. The most important renewable energy resources are hydropower, wind power and solar power. They can be large centralized systems like offshore wind parks or smaller and distributed ones, like rooftop PV systems.
The increasing share of renewable energies in the electricity mix also has a significant impact on the electric power grids. Grid operators must be able to deal with intermittent generation and changing load flows in order to ensure reliable supply and system security. When it comes to enabling reliable grid operation, requirements for generation plants are typically defined in standards. They include requirements for the behavior of the plants during grid faults or voltage dips and interconnection protection.
Examples for such standards are:
- IEEE 1547 for the US
- VDE-AR-N 4105 for Germany (VDE-AR-N 4110)
- ENA EREC G99 (succeeding G59) for the UK
Besides commissioning tests for the interconnection protection devices, routine maintenance tests may be required by standards or other regulations.
Power cables are typically used for the primary connection between the power network and renewable energy systems. Terrestrial and offshore cable solutions present a range of challenges, where commissioning and diagnostic testing helps to ensure flawless operation.
Routine checks of the renewable generator insulation system are crucial due to challenging atmospheric and temperature conditions. Dissipation / power factor & capacitance measurements are often performed to verify the integrity of the insulation system. Beside that various other testing and diagnostic options are available for creating informative assessments.
Grounding system testing
Grounding or Earthing systems must be in good condition and properly dimensioned to provide the best protection for personnel and ensure that the installation is working correctly. We have suitable solutions for testing soil resistivity, ground or earth potential rise (GPR, EPR), and ground resistance in small and extensive grounding systems. Our mobile hand-held HGT1 is ideal for measuring step- and touch voltages. In combination with PTM, all measurements can be recorded with GPS locations. This can save a lot of time, for example, in large solar parks.
During commissioning several performance tests are applied to circuit breakers to ensure proper functioning within the protection schema.
- Timing tests - The operation times of the main contacts and the auxiliary contacts are measured
- Release tests - The performance of the available releases have to be tested. This can be Undervoltage-releases, Shut releases or Indirect Current Releases
Later on, condition assessment methods are applied to determine the wear of critical components.
- Static contact resistance tests of the primary contacts to detect any damage caused by fault currents
- Trip coil current analysis to detect greasing issues (common issue)
- Travel measurement to assess the wear of the mechanical linkage
Transformer diagnostics (mostly cast-resin)
Induced voltage measurements and parallel partial discharge measurements are also essential tools for verifying the transformer insulation system in renewable energy testing. Limited space and the usage of cast-resin insulation systems often require energizing the transformer from the low voltage side for an accurate evaluation of the insulation system’s condition.
In addition, we provide common electrical tests, loss/power factor measurements, partial discharge analysis, frequency response analysis, and analysis of the dielectric response.
Our power transformer diagnostics solutions provide you with a tester informative diagnosis of the transformer’s condition quickly and easily.
Grounding tests for wind turbine rotors:
Most wind turbine lightning strikes hit the rotor blades. To reliably discharge the lightning, the resistance from the rotor to the earth at the base of the mast must be sufficiently low. Due to the long measurement leads required, the micro-ohm meter must have high output power and current to take accurate measurements. The battery-operated COMPANO 100 can cover this application as well.
Induced onsite partial discharge testing:
Renewable energy poses challenges due to the higher stress that fluctuating energy generation puts on the transformer insulation.
Cast resin transformers are often used for the most common failure of epoxy-resin insulation breakdown.
In locations with narrow space like wind turbines, induced voltage testing and PD measurements can help provide a comprehensive transformer diagnosis.