Grounding protection microgrid

How to ground a microgrid?

Grounding of microgrids is one of the most challenging topics for microgrid protection. In grid-connected mode, the system grounding is generally provided by the substation transformer.

Why is ground fault monitoring important for a dc microgrid?

In addition to the protection schemes, ground fault monitoring techniques for the DC microgrid are also important. Detecting a high-resistance grounding fault proves a tough and challenging task for DC system safety. Traditionally, the methods of AC injection and DC leakage are widely used .

What happens if a microgrid is grounded in grid-connected mode?

In grid-connected mode, the system grounding is generally provided by the substation transformer. If the microgrid or DER in the microgrid are grounded during grid-connected operation, it can result in bi-directional ground current flows, desensitization of ground current protection settings, and sympathetic tripping.

Why do microgrids need protection?

A second issue with protection of microgrids is that aside from the low fault currents in inverter-interfaced microgrids, there are also issues on account of varying levels of fault current caused by changing generation dispatch, and switching configurations, which can include the transition between grid-connected and islanded modes .

Why is a dc microgrid a multi-terminal protection system?

The topology of the DC microgrid is thus multi-terminal. And hence it becomes tricky to design a protection system flexible enough to deal with multiple numbers of terminals under a multi-directional power flow condition.

What protection devices are available for DC microgrids?

At present, the commercially available protection devices for DC microgrids are fuses and circuit breakers . Interruption of the current leads to the creation of an arc that cannot be easily extinguished in a DC system without the current crossing through zero. That’s still a challenge for applying the DC power system technologies.