E-grids protection – Improvement of Under-frequency Relay Setting for Local UFLS Protection

TECHNOLOGY DESCRIPTION

Background
The operation of under-frequency load shedding (UFLS) protection in power systems suffers from the lack of flexibility to different operating conditions. Wide-area solutions harvesting the fast developments in communication technology solve this issue, but at the same time have negative impact on robustness, transparency and reliability. In power-system protection field, this is usually unacceptable. Local solutions are therefore preferred, but not until now were they able to guaranty the high level of efficiency in variety of operating conditions.
Description of the Invention
The invention relates to improving current load-shedding criterion in under-frequency relays. Newly developed characteristic enables fine tuning of load-disconnection amount by implementing simple yet creative criterion based on locally measured Rate-of-Change-of-Frequency (RoCoF).

BENEFITS

Main Advantages
Invention enables achieving high level of efficiency compared to wide-area solutions and at the same time avoiding long-lasting and comprehensive re-setting procedures of existing UFLS protection schemes. Due to its local operation, no additional time delays are needed as already available signals within protection relays are used. Possibilities of over-shedding and consequential unacceptably high frequency over-shoots are completely avoided.

LIMITATIONS

N.A.

APPLICATIONS

This solution is flexible and adaptable, enabling integration in existing protection devices within electrical power systems and other advantages. The implementation of the Electric Grids Protection can save a lot of worries and cost to stakeholders, ranging from electricity producers, system operators down to individual consumers. It keeps the grids stable and in continuous operation. Without costly and timely modifications.

MATERIALS