Why Fanox Protection Relays are the right solution to protect renewable energy source systems.

Renewable energy is not a passing trend, are realities. Renewable energy is leading the energy transformation.

Infinite natural resources, such as sunlight, wind, rain, tides, waves, and geothermal heat, is derived from renewable energy.

We can distinguish two types of needs/protections:

  • Protection for interconnection with the Grid (ST)
  • Protection inside the farm (T1, T2…):
    • Wind Turbines
    • Solar Inverters


As main generator protection or backup of a main protection for installations inside or outside of the windmill.


Depending on the market practices, the economic costs, and the impact on network stability, there are different approaches to managing the wind farms.

With traditional relays, the management options are reduced because any failure of the power supply system would imply either the stop of the turbine or, what is worse, a non-protected generation scenario.

The electrical protection of the generator cannot be left in hands of an auxiliary powered relay in order to ensure a non-stop protection.

“Self-powered protection relays maintain the generator under protection whenever the turbine is connected to the MV network, including the energizing process, while other devices of the generator are still in the powering up process.”


SOLAR POWER – Challenges

There is a tendency on the market to go to bigger solar inverters. As the power increases (up to 7.5MVA and more) also the voltages are rising.

The market is demanding not only overcurrent protection, but full data registers and protection and control functions more complex: relays with reclosing capabilities, advanced communications…


To accommodate these new requirements, FANOX has worked in two directions:
A complete self-powered relay: it is important to have deficient self-powering levels, compact design, relays with the sensitive neutral channel for ZCT, oscillography records, full range of IEC and IEEE curves for selectivity or SHB to detect inrush current of the transformer.
A non-self-powered relay with advanced communications (TCP/IP protocols, IEC61850…) and those additional protection and control functions (ANSI 79, SOTF, 74CT, 46BC).

Market Trends

How to manage those impacts?

Until now, distributed generation units have been required to be disconnected during utility grid faults/islanding situations

  • Based on voltage, frequency, rate-of-change-frequency, or vector shift
  • Without any specific requirements to support a utility grid (HV Network)

Nowadays has become more common to require HV network stability support from distributed generation:

  • Prevent unnecessary disconnection during HV network faults and frequency disturbances
  • Support voltage and frequency during disturbances
    • P/ f and Q/ U control
    • Reactive current contribution during faults/ low voltage situations
    • More advanced MV protection and Islanding detection methods